Mode switching circuit for changing a signal path in an led tube lamp

ABSTRACT

A mode switching circuit is configured to change a signal path in a light-emitting diode (LED) tube lamp and comprises: at least one switch, configured to receive a filtered signal as a driving signal to drive an LED module in the LED tube lamp to emit light, and when a frequency of an external driving signal received by the LED tube lamp is higher than a mode switching frequency, output the driving signal to the LED module. The LED tube lamp comprises an auxiliary power module coupled to provide auxiliary power for the LED module to emit light; and the mode switching circuit is on a printed circuit board and is electrically connected to the LED module on a bendable circuit sheet in the LED tube lamp, wherein the bendable circuit sheet is disposed below the printed circuit board to be electrically connected to the printed circuit board by soldering.

This application is a continuation application of U.S. patentapplication Ser. No. 16/256,075, filed Jan. 24, 2019, which is acontinuation application of U.S. patent application Ser. No. 15/701,211,filed Sep. 11, 2017, which is a continuation-in-part application of U.S.patent application Ser. No. 15/258,471, filed Sep. 7, 2016, which is acontinuation-in-part application of U.S. patent application Ser. No.15/211,813, filed Jul. 15, 2016, which is a continuation-in-partapplication of U.S. patent application Ser. No. 15/150,458, filed May10, 2016, which is a continuation-in-part application of U.S. patentapplication Ser. No. 14/865,387, filed Sep. 25, 2015, the contents ofwhich applications are incorporated herein by reference in theirentirety. U.S. patent application Ser. No. 15/258,471 is also acontinuation-in-part application of U.S. patent application Ser. No.15/211,783, filed Jul. 15, 2016, which is a continuation-in-partapplication of U.S. patent application Ser. No. 15/087,088, filed Mar.31, 2016, which is a continuation-in-part application of U.S. patentapplication Ser. No. 14/865,387, filed Sep. 25, 2015, the contents ofeach of which are incorporated herein by reference in their entirety.

U.S. patent application Ser. No. 16/256,075 claims priority under 35U.S.C. 119(e) to Chinese Patent Applications Nos.: CN 201510651572.0,filed on 2015 Oct. 10; CN 201610043864.0, filed on 2016 Jan. 22; CN201610363805.1, filed on 2016 May 27; CN 201610990012.2, filed on 2016Nov. 10; CN 201611090717.5, filed on 2016 Nov. 30; CN 201710307204.3,filed on 2017 May 2, the contents of which priority applications areincorporated herein by reference in their entirety.

If any terms in this application conflict with terms used in anyapplication(s) to which this application claims priority, or termsincorporated by reference into this application or the application(s) towhich this application claims priority, a construction based on theterms as used or defined in this application should be applied.

TECHNICAL FIELD

The present disclosure relates to illumination devices, and moreparticularly relates to an LED tube lamp with a detection circuit fordetecting whether the LED tube lamp is being supplied by an incompatibleballast or for regulating the continuity of current to flow through itsLED unit(s) used to emit light, or a protection circuit for providingovervoltage and/or overcurrent protection.

RELATED ART

LED (light emitting diode) lighting technology is rapidly developing toreplace traditional incandescent and fluorescent lightings. LED tubelamps are mercury-free in comparison with fluorescent tube lamps thatneed to be filled with inert gas and mercury. Thus, it is not surprisingthat LED tube lamps are becoming a highly desired illumination optionamong different available lighting systems used in homes and workplaces,which used to be dominated by traditional lighting options such ascompact fluorescent light bulbs (CFLs) and fluorescent tube lamps.Benefits of LED tube lamps include improved durability and longevity andfar less energy consumption; therefore, when taking into account allfactors, they would typically be considered as a cost effective lightingoption.

Typical LED tube lamps have a lamp tube, a circuit board disposed insidethe lamp tube with light sources being mounted on the circuit board, andend caps accompanying a power supply provided at two ends of the lamptube with the electricity from the power supply transmitted to the lightsources through the circuit board. However, existing LED tube lamps havecertain drawbacks.

First, the typical circuit board is rigid and allows the entire lamptube to maintain a straight tube configuration when the lamp tube ispartially ruptured or broken, and this gives the user a false impressionthat the LED tube lamp remains usable and is likely to cause the user tobe electrically shocked upon handling or installation of the LED tubelamp.

Second, the rigid circuit board is typically electrically connected withthe end caps by way of wire bonding, in which the wires may be easilydamaged and even broken due to any move during manufacturing,transportation, and usage of the LED tube lamp and therefore may disablethe LED tube lamp.

Further, circuit design of current LED tube lamps mostly doesn't providesuitable solutions for complying with relevant certification standardsand for better compatibility with the driving structure using a ballastoriginally for a fluorescent lamp. For example, since there are usuallyno electronic components in a fluorescent lamp, it's fairly easy for afluorescent lamp to be certified under EMI (electromagneticinterference) standards and safety standards for lighting equipment asprovided by Underwriters Laboratories (UL). However, there are aconsiderable number of electronic components in an LED tube lamp, andtherefore consideration of the impacts caused by the layout (structure)of the electronic components is important, resulting in difficulties incomplying with such standards.

Common main types of electrical ballast include instant-start ballastand programmed-start ballast. Electrical ballast typically includes aresonant circuit and is designed to match the loading characteristics ofa fluorescent lamp in driving the fluorescent lamp. For example, forproperly starting a fluorescent lamp, the ballast provides drivingmethods respectively corresponding to the fluorescent lamp working as acapacitive device before emitting light, and working as a resistivedevice upon emitting light. But an LED is a nonlinear component withsignificantly different characteristics from a fluorescent lamp.Therefore, using an LED tube lamp with a ballast impacts the resonantcircuit design of the ballast, which may cause a compatibility problem.Generally, a programmed-start ballast will detect the presence of afilament in a fluorescent lamp, but traditional LED driving circuitscannot support the detection and may cause a failure of the filamentdetection and thus failure of the starting of the LED tube lamp.

SUMMARY

It's specially noted that the present disclosure may actually includeone or more inventions claimed currently or not yet claimed, and foravoiding confusion due to unnecessarily distinguishing between thosepossible inventions at the stage of preparing the specification, thepossible plurality of inventions herein may be collectively referred toas “the (present) invention” herein.

According to an aspect of the disclosed embodiment, a light emittingdiode (LED) tube lamp configured to receive an external driving signalincludes an LED module for emitting light, the LED module comprising anLED unit comprising an LED; a rectifying circuit for rectifying theexternal driving signal to produce a rectified signal, the rectifyingcircuit having a first output terminal and a second output terminal foroutputting the rectified signal; a filtering circuit connected to theLED module, and configured to provide a filtered signal for the LEDunit; and a protection circuit for providing protection for the LED tubelamp. The protection circuit includes a voltage divider comprising twoelements connected in series between the first and second outputterminals of the rectifying circuit, for producing a signal at aconnection node between the two elements; and a control circuit coupledto the connection node between the two elements, for receiving, anddetecting a state of, the signal at the connection node. The controlcircuit includes or is coupled to a switching circuit coupled to therectifying circuit, and the switching circuit is configured to betriggered on or off by the detected state, upon the external drivingsignal being input to the LED tube lamp, to allow discontinuous currentto flow through the LED unit.

According to another aspect of the disclosed invention, a light emittingdiode (LED) tube lamp configured to receive an external driving signalincludes: an LED module for emitting light, the LED module comprising anLED unit comprising an LED; a rectifying circuit for rectifying theexternal driving signal to produce a rectified signal, the rectifyingcircuit having a first output terminal and a second output terminal foroutputting the rectified signal; a filtering circuit connected to theLED module, and configured to provide a filtered signal for the LEDunit; and a detection circuit coupled between the rectifying circuit andthe LED module. The detection circuit includes a voltage dividercomprising two elements connected in series between the first and secondoutput terminals of the rectifying circuit, for producing a signal at aconnection node between the two elements, a control circuit coupled tothe connection node between the two elements, for receiving, anddetecting a state of, the signal at the connection node. The controlcircuit includes or is coupled to a switching circuit coupled to therectifying circuit, and the detection circuit is configured such thatwhen the external driving signal is input to the LED tube lamp, forpreventing an overcurrent condition the control circuit is triggered bythe detected state to output a signal to a control terminal of theswitching circuit to turn on or conduct the switching circuit, whereinthe conducting state of the switching circuit eventually dims the lightemitted by the LED unit.

According to another aspect of the disclosed embodiments, a lightemitting diode (LED) tube lamp configured to receive an external drivingsignal includes: a lamp tube; a first external connection terminal and asecond external connection terminal coupled to the lamp tube and forreceiving the external driving signal; an LED module for emitting light,the LED module comprising an LED unit comprising an LED; a rectifyingcircuit for rectifying the external driving signal to produce arectified signal, the rectifying circuit having a first output terminaland a second output terminal for outputting the rectified signal; afiltering circuit coupled to the rectifying circuit and the LED module;and a detection circuit coupled between the rectifying circuit and theLED module. The detection circuit includes a voltage divider comprisingtwo elements connected in series between the first and second outputterminals of the rectifying circuit, for producing a fraction voltage ata connection node between the two elements, and a controller coupled tothe connection node between the two elements, for receiving the fractionvoltage at the connection node. The LED tube lamp further includes aconverter circuit coupled between the controller and the LED module, forconverting a signal from the controller or the rectifying circuit into adriving signal for driving the LED module. The controller includes or iscoupled to a switch coupled to the converter circuit, and the detectioncircuit is configured such that when the fraction voltage is in adefined voltage range, the controller regulates the continuity ofcurrent to flow through the LED unit by alternately turning on and offthe switch.

In addition to using the ballast interface circuit or mode determinationcircuit to facilitate the LED tube lamp starting by the electricalballast, other innovations of mechanical structures of the LED tube lampdisclosed herein, such as the LED tube lamp including improvedstructures of a flexible circuit board or a bendable circuit sheet, andsoldering features of the bendable circuit sheet and a printed circuitboard bearing the power supply module of the LED tube lamp, may also beused to improve the stability of power supplying by the ballast and toprovide strengthened conductive path through, and connections between,the power supply module and the bendable circuit sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary exploded view schematically illustrating anexemplary LED tube lamp, according to certain embodiments;

FIG. 2 is a plan cross-sectional view schematically illustrating anexample of an end structure of a lamp tube of an LED tube lamp accordingto certain embodiments;

FIG. 3 is an exemplary plan cross-sectional view schematicallyillustrating an exemplary local structure of the transition region ofthe end of the lamp tube of FIG. 2;

FIG. 4 is a sectional view schematically illustrating an LED light stripthat includes a bendable circuit sheet with ends thereof passing acrossa transition region of a lamp tube of an LED tube lamp to be solderingbonded to the output terminals of the power supply according to anexemplary embodiment;

FIG. 5 is a cross-sectional view schematically illustrating a bi-layeredstructure of a bendable circuit sheet of an LED light strip of an LEDtube lamp according to an exemplary embodiment;

FIG. 6 is a perspective view schematically illustrating the solderingpad of a bendable circuit sheet of an LED light strip for solderingconnection with a printed circuit board of a power supply of an LED tubelamp according to an exemplary embodiment;

FIG. 7 is a perspective view schematically illustrating a circuit boardassembly composed of a bendable circuit sheet of an LED light strip anda printed circuit board of a power supply according to another exemplaryembodiment;

FIG. 8 is a perspective view schematically illustrating anotherexemplary arrangement of the circuit board assembly of FIG. 7;

FIG. 9 is a perspective view schematically illustrating a bendablecircuit sheet of an LED light strip formed with two conductive wiringlayers according to another exemplary embodiment;

FIG. 10 is a perspective view of an exemplary bendable circuit sheet anda printed circuit board of a power supply soldered to each other,according to certain embodiments;

FIGS. 11 to 13 are diagrams of an exemplary soldering process of abendable circuit sheet and a printed circuit board of a power supply,such as shown in the example of FIG. 10, according to certainembodiments;

FIG. 14A is a block diagram of an exemplary power supply system for anLED tube lamp according to some embodiments;

FIG. 14B is a block diagram of an exemplary power supply system for anLED tube lamp according to some embodiments;

FIG. 14C is a block diagram showing elements of an exemplary LED lampaccording to some embodiments;

FIG. 14D is a block diagram of an exemplary power supply system for anLED tube lamp according to some embodiments;

FIG. 14E is a block diagram showing elements of an LED lamp according tosome embodiments;

FIG. 15A is a schematic diagram of a rectifying circuit according tosome exemplary embodiments;

FIG. 15B is a schematic diagram of a rectifying circuit according tosome exemplary embodiments;

FIG. 15C is a schematic diagram of a rectifying circuit according tosome exemplary embodiments;

FIG. 15D is a schematic diagram of a rectifying circuit according tosome exemplary embodiments;

FIG. 16A is a block diagram of a filtering circuit according to someexemplary embodiments;

FIG. 16B is a schematic diagram of a filtering unit according to someexemplary embodiments;

FIG. 16C is a schematic diagram of a filtering unit according to someexemplary embodiments;

FIG. 17A is a schematic diagram of an LED module according to someexemplary embodiments;

FIG. 17B is a schematic diagram of an LED module according to someexemplary embodiments;

FIG. 18 is a block diagram of an LED lamp according to some exemplaryembodiments;

FIG. 19A is a block diagram of an LED lamp according to some exemplaryembodiments;

FIG. 19B is a schematic diagram of an anti-flickering circuit accordingto some exemplary embodiments;

FIG. 20A is a block diagram of an LED lamp according to some exemplaryembodiments;

FIG. 20B is a schematic diagram of a mode determination circuit in anLED lamp according to some exemplary embodiments;

FIG. 20C is a schematic diagram of a mode determination circuit in anLED lamp according to some exemplary embodiments;

FIG. 21A is a schematic diagram of a mode determination circuitaccording to some exemplary embodiments;

FIG. 21B is a schematic diagram of an LED tube lamp according to someexemplary embodiments, which includes an embodiment of the modedetermination circuit;

FIG. 21C is a schematic diagram of an LED tube lamp according to someexemplary embodiments, which includes an embodiment of the modedetermination circuit;

FIG. 22A is a block diagram of a driving circuit according to someembodiments;

FIG. 22B is a schematic diagram of a driving circuit according to someembodiments;

FIG. 22C is a schematic diagram of a driving circuit according to someembodiments;

FIG. 23A is a schematic diagram of a mode switching circuit in an LEDlamp according to some embodiments;

FIG. 23B is a schematic diagram of a mode switching circuit in an LEDlamp according to some embodiments;

FIG. 23C is a schematic diagram of a mode switching circuit in an LEDlamp according to some embodiments;

FIG. 23D is a schematic diagram of a mode switching circuit in an LEDlamp according to some embodiments;

FIG. 24A is a block diagram of an exemplary power supply module in anLED tube lamp according to some embodiments;

FIG. 24B is a block diagram of an exemplary power supply module in anLED tube lamp according to some embodiments; and

FIG. 24C is a schematic diagram of an auxiliary power module accordingto an embodiment.

DETAILED DESCRIPTION

The present disclosure provides a novel LED tube lamp, and also providessome features that can be used in LED lamps that are not LED tube lamps.The present disclosure will now be described in the followingembodiments with reference to the drawings.

The following descriptions of various implementations are presentedherein for purpose of illustration and giving examples only. Thisinvention is not intended to be exhaustive or to be limited to theprecise form disclosed. These example embodiments are justthat—examples—and many implementations and variations are possible thatdo not require the details provided herein. It should also be emphasizedthat the disclosure provides details of alternative examples, but suchlisting of alternatives is not exhaustive. Furthermore, any consistencyof detail between various examples should not be interpreted asrequiring such detail—it is impracticable to list every possiblevariation for every feature described herein. The language of the claimsshould be referenced in determining the requirements of the invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and/orthe present application, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

Referring to FIG. 1 and FIG. 2, a glass made lamp tube of an LED tubelamp according to an exemplary embodiment of the present invention hasstructure-strengthened end regions described as follows. The glass madelamp tube 1 includes a main body region 102, two rear end regions 101(or just end regions 101) respectively formed at two ends of the mainbody region 102, and end caps 3 that respectively sleeve the rear endregions 101. The outer diameter of at least one of the rear end regions101 is less than the outer diameter of the main body region 102. In theembodiment of FIGS. 1 and 2, the outer diameters of the two rear endregions 101 are less than the outer diameter of the main body region102. In addition, the surface of the rear end region 101 may be parallelto the surface of the main body region 102 in a cross-sectional view.Specifically, in some embodiments, the glass made lamp tube 1 isstrengthened at both ends, such that the rear end regions 101 are formedto be strengthened structures. In certain embodiments, the rear endregions 101 with strengthened structure are respectively sleeved withthe end caps 3, and the outer diameters of the end caps 3 and the mainbody region 102 have little or no differences. For example, the end caps3 may have the same or substantially the same outer diameters as that ofthe main body region 102 such that there is no gap between the end caps3 and the main body region 102. In this way, a supporting seat in apacking box for transportation of the LED tube lamp contacts not onlythe end caps 3 but also the lamp tube 1 and makes uniform the loadingson the entire LED tube lamp to avoid situations where only the end caps3 are forced, therefore preventing breakage at the connecting portionbetween the end caps 3 and the rear end regions 101 due to stressconcentration. The quality and the appearance of the product aretherefore improved.

In one embodiment, the end caps 3 and the main body region 102 havesubstantially the same outer diameters. These diameters may have atolerance for example within +/−0.2 millimeter (mm), or in some cases upto +/−1.0 millimeter (mm). Depending on the thickness of the end caps 3,the difference between an outer diameter of the rear end regions 101 andan outer diameter of the main body region 102 can be about 1 mm to about10 mm for typical product applications. In some embodiments, thedifference between the outer diameter of the rear end regions 101 andthe outer diameter of the main body region 102 can be about 2 mm toabout 7 mm.

Referring to FIG. 2, the lamp tube 1 is further formed with a transitionregion 103 between the main body region 102 and the rear end regions101. In one embodiment, the transition region 103 is a curved regionformed to have cambers at two ends to smoothly connect the main bodyregion 102 and the rear end regions 101, respectively. For example, thetwo ends of the transition region 103 may be arc-shaped in across-section view along the axial direction of the lamp tube 1.Furthermore, one of the cambers connects the main body region 102 whilethe other one of the cambers connects the rear end region 101. In someembodiments, the arc angle of the cambers is greater than 90 degreeswhile the outer surface of the rear end region 101 is a continuoussurface in parallel with the outer surface of the main body region 102when viewed from the cross-section along the axial direction of the lamptube. In other embodiments, the transition region 103 can be withoutcurve or arc in shape. In certain embodiments, the length of thetransition region 103 along the axial direction of the lamp tube 1 isbetween about 1 mm to about 4 mm. Upon experimentation, it was foundthat when the length of the transition region 103 along the axialdirection of the lamp tube 1 is less than 1 mm, the strength of thetransition region would be insufficient; when the length of thetransition region 103 along the axial direction of the lamp tube 1 ismore than 4 mm, the main body region 102 would be shorter and thedesired illumination surface would be reduced, and the end caps 3 wouldbe longer and the more materials for the end caps 3 would be needed.

As can be seen in FIG. 2, and in the more detailed closer-up depictionin FIG. 3, in certain embodiments, in the transition region 103, thelamp tube 1 narrows, or tapers to have a smaller diameter when movingalong the length of the lamp tube 1 from the main region 102 to the endregion 101. The tapering/narrowing may occur in a continuous, smoothmanner (e.g., to be a smooth curve without any linear angles). Byavoiding angles, in particular any acute angles, the lamp tube 1 is lesslikely to break or crack under pressure.

Referring to FIG. 3, in certain embodiments, the lamp tube 1 is made ofglass, and has a rear end region 101, a main body region 102, and atransition region 103. The transition region 103 has two arc-shapedcambers at both ends to from an S shape; one camber positioned near themain body region 102 is convex outwardly, while the other camberpositioned near the rear end region 101 is concaved inwardly. Generallyspeaking, the radius of curvature, R1, of the camber/arc between thetransition region 103 and the main body region 102 is smaller than theradius of curvature, R2, of the camber/arc between the transition region103 and the rear end region 101.

Referring to FIG. 4 and FIG. 9, an LED tube lamp in accordance with anexemplary embodiment includes a lamp tube 1, which may be formed ofglass and may be referred to herein as a glass lamp tube 1; two end capsrespectively disposed at two ends of the glass lamp tube 1; a powersupply 5; and an LED light strip 2 disposed inside the glass lamp tube1. For example, the end cap and the lamp tube are connected to eachother in an adhesive manner such that there is no gap between the endcap and the lamp tube or there are extremely small gaps between the endcap and the lamp tube. The glass lamp tube 1 extending in a firstdirection along a length of the glass lamp tube 1 includes a main bodyregion, a rear end region, and a transition region connecting the mainbody region and the rear end region, wherein the main body region andthe rear end region are substantially parallel. As shown in theembodiment of FIG. 4, the bendable circuit sheet 2 (as an embodiment ofthe light strip 2) passes through a transition region to be soldered ortraditionally wire-bonded with the power supply 5, and then the end capof the LED tube lamp is adhered to the transition region, respectivelyto form a complete LED tube lamp. As discussed herein, a transitionregion of the lamp tube refers to regions outside a central portion ofthe lamp tube and inside terminal ends of the lamp tube. For example, acentral portion of the lamp tube may have a constant diameter, and eachtransition region between the central portion and a terminal end of thelamp tube may have a changing diameter (e.g., at least part of thetransition region may become more narrow moving in a direction from thecentral portion to the terminal end of the lamp tube). End capsincluding the power supply may be disposed at the terminal ends of thelamp tube, and may cover part of the transition region.

With reference to FIG. 5, in this embodiment, the LED light strip 2 isfixed by the adhesive sheet 4 to an inner circumferential surface of thelamp tube 1, so as to increase the light illumination angle of the LEDtube lamp and broaden the viewing angle to be greater than 330 degrees.

In some embodiments, the light strip 2 may be an elongated aluminumplate, FR 4 board, or a bendable circuit sheet. When the lamp tube 1 ismade of glass, adopting a rigid aluminum plate or FR4 board would make abroken lamp tube, e.g., broken into two parts, remain a straight shapeso that a user may be under a false impression that the LED tube lamp isstill usable and fully functional, and it is easy for the user to incurelectric shock upon handling or installation of the LED tube lamp.Because of added flexibility and bendability of the flexible substratefor the LED light strip 2, the problem faced by the aluminum plate, FR4board, or conventional 3-layered flexible board having inadequateflexibility and bendability, are thereby addressed. In certainembodiments, a bendable circuit sheet is adopted as the LED light strip2 because such an LED light strip 2 would not allow a ruptured or brokenlamp tube to maintain a straight shape and therefore would instantlyinform the user of the disability of the LED tube lamp to avoid possiblyincurred electrical shock. The following are further descriptions of abendable circuit sheet that may be used as the LED light strip 2.

Referring to FIG. 5, in one embodiment, the LED light strip 2 includes abendable circuit sheet having a conductive wiring layer 2 a and adielectric layer 2 b that are arranged in a stacked manner, wherein thewiring layer 2 a and the dielectric layer 2 b have same areas. The LEDlight source 202 is disposed on one surface of the wiring layer 2 a, thedielectric layer 2 b is disposed on the other surface of the wiringlayer 2 a that is away from the LED light sources 202 (e.g., a second,opposite surface from the first surface on which the LED light source202 is disposed). The wiring layer 2 a is electrically connected to thepower supply 5 to carry direct current (DC) signals. Meanwhile, thesurface of the dielectric layer 2 b away from the wiring layer 2 a(e.g., a second surface of the dielectric layer 2 b opposite a firstsurface facing the wiring layer 2 a) is fixed to the innercircumferential surface of the lamp tube 1 by means of the adhesivesheet 4. The portion of the dielectric layer 2 b fixed to the innercircumferential surface of the lamp tube 1 may substantially conform tothe shape of the inner circumferential surface of the lamp tube 1. Thewiring layer 2 a can be a metal layer or a power supply layer includingwires such as copper wires.

In another embodiment, the outer surface of the wiring layer 2 a or thedielectric layer 2 b may be covered with a circuit protective layer madeof an ink with function of resisting soldering and increasingreflectivity. Alternatively, the dielectric layer can be omitted and thewiring layer can be directly bonded to the inner circumferential surfaceof the lamp tube, and the outer surface of the wiring layer 2 a may becoated with the circuit protective layer. Whether the wiring layer 2 ahas a one-layered, or two-layered structure, the circuit protectivelayer can be adopted. In some embodiments, the circuit protective layeris disposed only on one side/surface of the LED light strip 2, such asthe surface having the LED light source 202. In some embodiments, thebendable circuit sheet is a one-layered structure made of just onewiring layer 2 a, or a two-layered structure made of one wiring layer 2a and one dielectric layer 2 b, and thus is more bendable or flexible tocurl when compared with the conventional three-layered flexiblesubstrate (one dielectric layer sandwiched with two wiring layers). As aresult, the bendable circuit sheet of the LED light strip 2 can beinstalled in a lamp tube with a customized shape or non-tubular shape,and fitly mounted to the inner surface of the lamp tube. The bendablecircuit sheet closely mounted to the inner surface of the lamp tube ispreferable in some cases. In addition, using fewer layers of thebendable circuit sheet improves the heat dissipation and lowers thematerial cost.

Nevertheless, the bendable circuit sheet is not limited to beingone-layered or two-layered; in other embodiments, the bendable circuitsheet may include multiple layers of the wiring layers 2 a and multiplelayers of the dielectric layers 2 b, in which the dielectric layers 2 band the wiring layers 2 a are sequentially stacked in a staggeredmanner, respectively. These stacked layers may be between the outermostwiring layer 2 a (with respect to the inner circumferential surface ofthe lamp tube), which has the LED light source 202 disposed thereon, andthe inner circumferential surface of the lamp tube, and may beelectrically connected to the power supply 5. Moreover, in someembodiments, the length of the bendable circuit sheet is greater thanthe length of the lamp tube (not including the length of the two endcaps respectively connected to two ends of the lamp tube), or at leastgreater than a central portion of the lamp tube between two transitionregions (e.g., where the circumference of the lamp tube narrows) oneither end. In one embodiment, the longitudinally projected length ofthe bendable circuit sheet as the LED light strip 2 is larger than thelength of the lamp tube.

Referring to FIG. 4, FIG. 6, and FIG. 9, in some embodiments, the LEDlight strip 2 is disposed inside the glass lamp tube 1 with a pluralityof LED light sources 202 mounted on the LED light strip 2. The LED lightstrip 2 includes a bendable circuit sheet electrically connecting theLED light sources 202 with the power supply 5. The power supply 5 orpower supply module may include various elements for providing power tothe LED light strip 2. For example, the elements may include powerconverters or other circuit elements for providing power to the LEDlight strip 2. For example, the power supply may include a circuit thatconverts or generates power based on a received voltage, in order tosupply power to operate an LED module and the LED light sources 202 ofthe LED tube lamp. A power supply, as described in connection with powersupply 5, may be otherwise referred to as a power conversion module orcircuit or a power module. A power conversion module or circuit, orpower module, may supply or provide power from external signal(s), suchas from an AC power line or from a ballast, to an LED module and the LEDlight sources 202.

In some embodiments, the length of the bendable circuit sheet is largerthan the length of the glass lamp tube 1, and the bendable circuit sheethas a first end and a second end opposite to each other along the firstdirection, and at least one of the first and second ends of the bendablecircuit sheet is bent away from the glass lamp tube 1 to form a freelyextending end portion 21 along a longitudinal direction of the glasslamp tube 1. The freely extendable end portion 21 is an integral portionof the bendable circuit sheet 2. In some embodiments, if two powersupplies 5 are adopted, then the other of the first and second endsmight also be bent away from the glass lamp tube 1 to form anotherfreely extending end portion 21 along the longitudinal direction of theglass lamp tube 1. The freely extending end portion 21 is electricallyconnected to the power supply 5. Specifically, in some embodiments, thepower supply 5 has soldering pads “a” which are capable of beingsoldered with the soldering pads “b” of the freely extending end portion21 by soldering material “g”.

Referring to FIG. 9, in one embodiment, the LED light strip 2 includes abendable circuit sheet having in sequence a first wiring layer 2 a, adielectric layer 2 b, and a second wiring layer 2 c. The thickness ofthe second wiring layer 2 c (e.g., in a direction in which the layers 2a through 2 c are stacked) is greater than that of the first wiringlayer 2 a, and the length of the LED light strip 2 is greater than thatof the lamp tube 1, or at least greater than a central portion of thelamp tube between two transition regions (e.g., where the circumferenceof the lamp tube narrows) on either end. The end region of the lightstrip 2 extending beyond the end portion of the lamp tube 1 withoutdisposition of the light source 202 (e.g., an end portion without lightsources 202 disposed thereon) may be formed with two separate throughholes 203 and 204 to respectively electrically communicate the firstwiring layer 2 a and the second wiring layer 2 c. The through holes 203and 204 are not communicated to each other to avoid short.

Furthermore, the first wiring layer 2 a and the second wiring layer 2 cof the end region of the LED light strip 2 that extends beyond the endportion of the lamp tube 1 without disposition of the light source 202can be used to accomplish the circuit layout of a power supply module sothat the power supply module can be directly disposed on the bendablecircuit sheet of the LED light strip 2.

The power supply 5 according to some embodiments of the presentinvention can be formed on a single printed circuit board provided witha power supply module as depicted for example in FIG. 4.

In still another embodiment, the connection between the power supply 5and the LED light strip 2 may be accomplished via tin soldering, rivetbonding, or welding. One way to secure the LED light strip 2 is toprovide the adhesive sheet 4 at one side thereof and adhere the LEDlight strip 2 to the inner surface of the lamp tube 1 via the adhesivesheet 4. Two ends of the LED light strip 2 can be either fixed to ordetached from the inner surface of the lamp tube 1.

In case where two ends of the LED light strip 2 are fixed to the innersurface of the lamp tube and that the LED light strip 2 is connected tothe power supply 5 via wire-bonding, any movement in subsequenttransportation is likely to cause the bonded wires to break. Therefore,a useful option for the connection between the light strip 2 and thepower supply 5 could be soldering. Specifically, referring to FIG. 4,the ends of the LED light strip 2 including the bendable circuit sheetare arranged to pass over the strengthened transition region and bedirectly solder bonded to an output terminal of the power supply 5. Thismay improve the product quality by avoiding using wires and/or wirebonding.

Referring to FIG. 6, an output terminal of the printed circuit board ofthe power supply 5 may have soldering pads “a” provided with an amountof solder (e.g., tin solder) with a thickness sufficient to later form asolder joint. Correspondingly, the ends of the LED light strip 2 mayhave soldering pads “b”. The soldering pads “a” on the output terminalof the printed circuit board of the power supply 5 are soldered to thesoldering pads “b” on the LED light strip 2 via the tin solder on thesoldering pads “a”. The soldering pads “a” and the soldering pads “b”may be face to face during soldering such that the connection betweenthe LED light strip 2 and the printed circuit board of the power supply5 is the most firm. However, this kind of soldering typically includesthat a thermo-compression head presses on the rear surface of the LEDlight strip 2 and heats the tin solder, i.e. the LED light strip 2intervenes between the thermo-compression head and the tin solder, andtherefore may easily cause reliability problems.

Referring again to FIG. 6, two ends of the LED light strip 2 detachedfrom the inner surface of the lamp tube 1 are formed as freely extendingportions 21, while most of the LED light strip 2 is attached and securedto the inner surface of the lamp tube 1. One of the freely extendingportions 21 has the soldering pads “b” as mentioned above. Uponassembling of the LED tube lamp, the freely extending end portions 21along with the soldered connection of the printed circuit board of thepower supply 5 and the LED light strip 2 would be coiled, curled up ordeformed to be fittingly accommodated inside the lamp tube 1. When thebendable circuit sheet of the LED light strip 2 includes in sequence thefirst wiring layer 2 a, the dielectric layer 2 b, and the second wiringlayer 2 c as shown in FIG. 9, the freely extending end portions 21 canbe used to accomplish the connection between the first wiring layer 2 aand the second wiring layer 2 c and arrange the circuit layout of thepower supply 5.

In this embodiment, during the connection of the LED light strip 2 andthe power supply 5, the soldering pads “b” and the soldering pads “a”and the LED light sources 202 are on surfaces facing toward the samedirection and the soldering pads “b” on the LED light strip 2 are eachformed with a through hole such that the soldering pads “b” and thesoldering pads “a” communicate with each other via the through holes.When the freely extending end portions 21 are deformed due tocontraction or curling up, the soldered connection of the printedcircuit board of the power supply 5 and the LED light strip 2 exerts alateral tension on the power supply 5. Furthermore, the solderedconnection of the printed circuit board of the power supply 5 and theLED light strip 2 also exerts a downward tension on the power supply 5when compared with the situation where the soldering pads “a” of thepower supply 5 and the soldering pads “b” of the LED light strip 2 areface to face. This downward tension on the power supply 5 comes from thetin solders inside the through holes and forms a stronger and moresecure electrical connection between the LED light strip 2 and the powersupply 5. As described above, the freely extending portions 21 may bedifferent from a fixed portion of the LED light strip 2 in that theyfixed portion may conform to the shape of the inner surface of the lamptube 1 and may be fixed thereto, while the freely extending portion 21may have a shape that does not conform to the shape of the lamp tube 1.For example, there may be a space between an inner surface of the lamptube 1 and the freely extending portion 21. As shown in FIG. 6, thefreely extending portion 21 may be bent away from the lamp tube 1.

The through hole communicates the soldering pad “a” with the solderingpad “b” so that the solder (e.g., tin solder) on the soldering pads “a”passes through the through holes and finally reach the soldering pads“b”. A smaller through hole would make it difficult for the tin solderto pass. The tin solder accumulates around the through holes uponexiting the through holes and condenses to form a solder ball “g” with alarger diameter than that of the through holes upon condensing. Such asolder ball “g” functions as a rivet to further increase the stabilityof the electrical connection between the soldering pads “a” on the powersupply 5 and the soldering pads “b” on the LED light strip 2.

Referring to FIGS. 7 and 8, in another embodiment, the LED light strip 2and the power supply 5 may be connected by utilizing a circuit boardassembly 25 instead of solder bonding. The circuit board assembly 25 hasa long circuit sheet 251 and a short circuit board 253 that are adheredto each other with the short circuit board 253 being adjacent to theside edge of the long circuit sheet 251. The short circuit board 253 maybe provided with power supply module 250 to form the power supply 5. Theshort circuit board 253 is stiffer or more rigid than the long circuitsheet 251 to be able to support the power supply module 250.

The long circuit sheet 251 may be the bendable circuit sheet of the LEDlight strip including a wiring layer 2 a as shown in FIG. 5. The wiringlayer 2 a of the long circuit sheet 251 and the power supply module 250may be electrically connected in various manners depending on the demandin practice. As shown in FIG. 7, the power supply module 250 and thelong circuit sheet 251 having the wiring layer 2 a on one surface are onthe same side of the short circuit board 253 such that the power supplymodule 250 is directly connected to the long circuit sheet 251. As shownin FIG. 8, alternatively, the power supply module 250 and the longcircuit sheet 251 including the wiring layer 2 a on one surface are onopposite sides of the short circuit board 253 such that the power supplymodule 250 is directly connected to the short circuit board 253 andindirectly connected to the wiring layer 2 a of the LED light strip 2 byway of the short circuit board 253.

As shown in FIG. 7, in one embodiment, the long circuit sheet 251 andthe short circuit board 253 are adhered together first, and the powersupply module 250 is subsequently mounted on the wiring layer 2 a of thelong circuit sheet 251 serving as the LED light strip 2. The longcircuit sheet 251 of the LED light strip 2 herein is not limited toinclude only one wiring layer 2 a and may further include another wiringlayer such as the wiring layer 2 c shown in FIG. 9. The light sources202 are disposed on the wiring layer 2 a of the LED light strip 2 andelectrically connected to the power supply 5 by way of the wiring layer2 a. As shown in FIG. 8, in another embodiment, the long circuit sheet251 of the LED light strip 2 may include a wiring layer 2 a and adielectric layer 2 b. The dielectric layer 2 b may be adhered to theshort circuit board 253 first and the wiring layer 2 a is subsequentlyadhered to the dielectric layer 2 b and extends to the short circuitboard 253. All these embodiments are within the scope of applying thecircuit board assembly concept of the present invention.

In the above-mentioned embodiments, the short circuit board 253 may havea length generally of about 15 mm to about 40 mm and in some preferableembodiments about 19 mm to about 36 mm, while the long circuit sheet 251may have a length generally of about 800 mm to about 2800 mm and in someembodiments of about 1200 mm to about 2400 mm. A ratio of the length ofthe short circuit board 253 to the length of the long circuit sheet 251ranges from, for example, about 1:20 to about 1:200.

When the ends of the LED light strip 2 are not fixed on the innersurface of the lamp tube 1, the connection between the LED light strip 2and the power supply 5 via soldering bonding would likely not firmlysupport the power supply 5, and it may be necessary to dispose the powersupply 5 inside the end cap. For example, a longer end cap to haveenough space for receiving the power supply 5 may be used. However, thiswill reduce the length of the lamp tube under the prerequisite that thetotal length of the LED tube lamp is fixed according to the productstandard, and may therefore decrease the effective illuminating areas.

Referring to FIG. 10 to FIG. 13, FIG. 10 is a perspective view of abendable circuit sheet 200 and a printed circuit board 420 of a powersupply 400 soldered to each other and FIG. 11 to FIG. 13 are diagrams ofa soldering process of the bendable circuit sheet 200 and the printedcircuit board 420 of the power supply 400. In the embodiment, thebendable circuit sheet 200 and the freely extending end portion 21 havethe same structure. The freely extending end portion 21 comprises theportions of two opposite ends of the bendable circuit sheet 200 and isutilized for being connected to the printed circuit board 420. Thebendable circuit sheet 200 and the power supply 400 are electricallyconnected to each other by soldering. The bendable circuit sheet 200comprises a circuit layer 200 a and a circuit protection layer 200 cover a side of the circuit layer 200 a. Moreover, the bendable circuitsheet 200 comprises two opposite surfaces which are a first surface 2001and a second surface 2002. The first surface 2001 is the one on thecircuit layer 200 a and away from the circuit protection layer 200 c.The second surface 2002 is the other one on the circuit protection layer200 c and away from the circuit layer 200 a. Several LED light sources202 are disposed on the first surface 2001 and are electricallyconnected to circuits of the circuit layer 200 a. The circuit protectionlayer 200 c is made by polyimide (PI) having less thermal conductivitybut being beneficial to protect the circuits. The first surface 2001 ofthe bendable circuit sheet 200 comprises soldering pads “b”. Solderingmaterial “g” can be placed on the soldering pads “b”. In one embodiment,the bendable circuit sheet 200 further comprises a notch “f”. The notch“f” is disposed on an edge of the end of the bendable circuit sheet 200soldered to the printed circuit board 420 of the power supply 400. Insome embodiments instead of a notch, a hole near the edge of the end ofthe bendable circuit sheet 200 may be used, which may thus provideadditional contact material between the printed circuit board 420 andthe bendable circuit sheet 200, thereby providing a stronger connection.The printed circuit board 420 comprises a power circuit layer 420 a andsoldering pads “a”. Moreover, the printed circuit board 420 comprisestwo opposite surfaces which are a first surface 421 and a second surface422. The second surface 422 is the one on the power circuit layer 420 a.The soldering pads “a” are respectively disposed on the first surface421 and the second surface 422. The soldering pads “a” on the firstsurface 421 are corresponding to those on the second surface 422.Soldering material “g” can be placed on the soldering pad “a”. In oneembodiment, considering the stability of soldering and the optimizationof automatic process, the bendable circuit sheet 200 is disposed belowthe printed circuit board 420 (their relative positions are shown inFIG. 11). That is to say, the first surface 2001 of the bendable circuitsheet 200 is connected to the second surface 422 of the printed circuitboard 420. Also, as shown, the soldering material “g” can contact,cover, and be soldered to a top surface of the bendable circuit sheet200 (e.g., first surface 2001), end side surfaces of soldering pads “a,”soldering pad “b,” and power circuit layer 420 a formed at an edge ofthe printed circuit board 420, and a top surface of soldering pad “a” atthe top surface 421 of the printed circuit board 420. In addition, thesoldering material “g” can contact side surfaces of soldering pads “a,”soldering pad “b,” and power circuit layer 420 a formed at a hole in theprinted circuit board 420 and/or at a hole or notch in bendable circuitsheet 200. The soldering material may therefore form a bump-shapedportion covering portions of the bendable circuit sheet 200 and theprinted circuit board 420, and a rod-shaped portion passing through theprinted circuit board 420 and through a hole or notch in the bendablecircuit sheet 200. The two portions (e.g., bump-shaped portion androd-shaped portion) may serve as a rivet, for maintaining a strongconnection between the bendable circuit sheet 200 and the printedcircuit board 420.

As shown in FIG. 12 and FIG. 13, in an exemplary soldering process ofthe bendable circuit sheet 200 and the printed circuit board 420, thecircuit protection layer 200 c of the bendable circuit sheet 200 isplaced on a supporting table 42 (i.e., the second surface 2002 of thebendable circuit sheet 200 contacts the supporting table 42) in advanceof soldering. The soldering pads “a” on the second surface 422 of theprinted circuit board 420 directly sufficiently contact the solderingpads “b” on the first surface 2001 of the bendable circuit sheet 200.And then a heating head 41 presses on a portion of the solderingmaterial “g” where the bendable circuit sheet 200 and the printedcircuit board 420 are soldered to each other. When soldering, thesoldering pads “b” on the first surface 2001 of the bendable circuitsheet 200 directly contact the soldering pads “a” on the second surface422 of the printed circuit board 420, and the soldering pads “a” on thefirst surface 421 of the printed circuit board 420 contact the solderingmaterial “g,” which is pressed on by heating head 41. Under thecircumstances, the heat from the heating heads 41 can directly transmitthrough the soldering pads “a” on the first surface 421 of the printedcircuit board 420 and the soldering pads “a” on the second surface 422of the printed circuit board 420 to the soldering pads “b” on the firstsurface 2001 of the bendable circuit sheet 200. The transmission of theheat between the heating heads 41 and the soldering pads “a” and “b”won't be affected by the circuit protection layer 200 c which hasrelatively less thermal conductivity, since the circuit protection layer200 c is not between the heating head 41 and the circuit layer 200 a.Consequently, the efficiency and stability regarding the connections andsoldering process of the soldering pads “a” and “b” of the printedcircuit board 420 and the bendable circuit sheet 200 can be improved. Asshown in the exemplary embodiment of FIG. 12, the printed circuit board420 and the bendable circuit sheet 200 are firmly connected to eachother by the soldering material “g”. Components between the virtual lineM and the virtual line N of FIG. 12 from top to bottom are the solderingpads “a” on the first surface 421 of printed circuit board 420, thepower circuit layer 420 a, the soldering pads “a” on the second surface422 of printed circuit board 420, the soldering pads “b” on the firstsurface 2001 of bendable circuit sheet 200, the circuit layer 200 a ofthe bendable circuit sheet 200, and the circuit protection layer 200 cof the bendable circuit sheet 200. The connection of the printed circuitboard 420 and the bendable circuit sheet 200 are firm and stable. Thesoldering material “g” may extend higher than the soldering pads “a” onthe first surface 421 of printed circuit board 420 and may fill in otherspaces, as described above.

In other embodiments, an additional circuit protection layer (e.g., PIlayer) can be disposed over the first surface 2001 of the circuit layer200 a. For example, the circuit layer 200 a may be sandwiched betweentwo circuit protection layers, and therefore the first surface 2001 ofthe circuit layer 200 a can be protected by the circuit protectionlayer. A part of the circuit layer 200 a (the part having the solderingpads “b”) is exposed for being connected to the soldering pads “a” ofthe printed circuit board 420. Other parts of the circuit layer 200 aare exposed by the additional circuit protection layer so they canconnect to LED light sources 202. Under these circumstances, a part ofthe bottom of the each LED light source 202 contacts the circuitprotection layer on the first surface 2001 of the circuit layer 200 a,and another part of the bottom of the LED light source 202 contacts thecircuit layer 200 a.

According to the exemplary embodiments shown in FIG. 10 to FIG. 13, theprinted circuit board 420 further comprises through holes “h” passingthrough the soldering pads “a”. In an automatic soldering process, whenthe heating head 41 automatically presses the printed circuit board 420,the soldering material “g” on the soldering pads “a” can be pushed intothe through holes “h” by the heating head 41 accordingly, which fits theneed of automatic process.

Next, examples of the circuit design and using of the power supplymodule 250 are described as follows.

FIG. 14A is a block diagram of a power supply system for an LED tubelamp according to an embodiment.

Referring to FIG. 14A, an AC power supply 508 is used to supply an ACsupply signal, and may be an AC powerline with a voltage rating, forexample, of 100-277 volts and a frequency rating, for example, of 50 or60 Hz. A lamp driving circuit 505 receives and then converts the ACsupply signal into an AC driving signal as an external driving signal(external, in that it is external to the LED tube lamp). Lamp drivingcircuit 505 may be for example an electronic ballast used to convert theAC powerline into a high-frequency high-voltage AC driving signal.Common types of electronic ballast include instant-start ballast,programmed-start or rapid-start ballast, etc., which may all beapplicable to the LED tube lamp of the present disclosure. The voltageof the AC driving signal is in some embodiments higher than 300 volts,and is in some embodiments in the range of about 400-700 volts. Thefrequency of the AC driving signal is in some embodiments higher than 10k Hz, and is in some embodiments in the range of about 20 k-50 k Hz. TheLED tube lamp 500 receives an external driving signal and is thus drivento emit light via the LED light sources 202. In one embodiment, theexternal driving signal comprises the AC driving signal from lampdriving circuit 505. In one embodiment, LED tube lamp 500 is in adriving environment in which it is power-supplied at only one end caphaving two conductive pins 501 and 502, which are coupled to lampdriving circuit 505 to receive the AC driving signal. The two conductivepins 501 and 502 may be electrically and physically connected to, eitherdirectly or indirectly, the lamp driving circuit 505. The two conductivepins 501 and 502 may be formed, for example, of a conductive materialsuch as a metal. The conductive pins may have, for example, a protrudingrod-shape, or a ball shape. Conductive pins such as 501 and 502 may begenerally referred to as external connection terminals, for connectingthe LED tube lamp 500 to an external socket. Under such circumstance,conductive pin 501 can be referred to as the first external connectionterminal, and conductive pin 502 can be referred to as the secondexternal connection terminal. The external connection terminals may havean elongated shape, a ball shape, or in some cases may even be flat ormay have a female-type connection for connecting to protruding maleconnectors in a lamp socket. In another embodiment, the numbers of theconductive pins may more than two. For example, the numbers of theconductive pins can vary depending on the needs of the application.

In some embodiments, lamp driving circuit 505 may be omitted and istherefore depicted by a dotted line. In one embodiment, if lamp drivingcircuit 505 is omitted, AC power supply 508 is directly connected topins 501 and 502, which then receive the AC supply signal as an externaldriving signal.

In addition to the above use with a single-end power supply, LED tubelamp 500 may instead be used with a dual-end power supply to one pin ateach of the two ends of an LED lamp tube. FIG. 14B is a block diagram ofa power supply system for an LED tube lamp according to one embodiment.Referring to FIG. 14B, compared to that shown in FIG. 14A, pins 501 and502 are respectively disposed at the two opposite end caps of LED tubelamp 500, forming a single pin at each end of LED tube lamp 500, withother components and their functions being the same as those in FIG.14A.

FIG. 14C is a block diagram showing elements of an LED lamp according toan exemplary embodiment. Referring to FIG. 14C, the power supply module250 of the LED lamp may include a rectifying circuit 510 and a filteringcircuit 520, and may also include some components of an LED lightingmodule 530. Rectifying circuit 510 is coupled to pins 501 and 502 toreceive and then rectify an external driving signal, so as to output arectified signal at output terminals 511 and 512. The external drivingsignal may be the AC driving signal or the AC supply signal describedwith reference to FIGS. 14A and 14B, or may even be a DC signal, whichin some embodiments does not alter the LED lamp of the presentinvention. Filtering circuit 520 is coupled to the first rectifyingcircuit for filtering the rectified signal to produce a filtered signal.For instance, filtering circuit 520 is coupled to terminals 511 and 512to receive and then filter the rectified signal, so as to output afiltered signal at output terminals 521 and 522. LED lighting module 530is coupled to filtering circuit 520, to receive the filtered signal foremitting light. For instance, LED lighting module 530 may include acircuit coupled to terminals 521 and 522 to receive the filtered signaland thereby to drive an LED unit (e.g., LED light sources 202 on an LEDlight strip 2, as discussed above, and not shown in FIG. 14C). Forexample, as described in more detail below, LED lighting module 530 mayinclude a driving circuit coupled to an LED module to emit light.Details of these operations are described in below descriptions ofcertain embodiments.

In some embodiments, although there are two output terminals 511 and 512and two output terminals 521 and 522 in embodiments of these Figs., inpractice the number of ports or terminals for coupling betweenrectifying circuit 510, filtering circuit 520, and LED lighting module530 may be one or more depending on the needs of signal transmissionbetween the circuits or devices.

In addition, the power supply module of the LED lamp described in FIG.14C, and embodiments of the power supply module of an LED lamp describedbelow, may each be used in the LED tube lamp 500 in FIGS. 14A and 14B,and may instead be used in any other type of LED lighting structurehaving two conductive pins used to conduct power, such as LED lightbulbs, personal area lights (PAL), plug-in LED lamps with differenttypes of bases (such as types of PL-S, PL-D, PL-T, PL-L, etc.), etc.

FIG. 14D is a block diagram of a power supply system for an LED tubelamp according to an embodiment. Referring to FIG. 14D, an AC powersupply 508 is used to supply an AC supply signal. A lamp driving circuit505 receives and then converts the AC supply signal into an AC drivingsignal. An LED tube lamp 500 receives an AC driving signal from lampdriving circuit 505 and is thus driven to emit light. In thisembodiment, LED tube lamp 500 is power-supplied at its both end capsrespectively having two pins 501 and 502 and two pins 503 and 504, whichare coupled to lamp driving circuit 505 to concurrently receive the ACdriving signal to drive an LED unit (not shown) in LED tube lamp 500 toemit light. AC power supply 508 may be, e.g., the AC powerline, and lampdriving circuit 505 may be a stabilizer or an electronic ballast. Itshould be noted that different pins or external connection terminalsdescribed throughout this specification may be named as firstpin/external connection terminal, second pin/external connectionterminal, third pin/external connection terminal, etc., for discussionpurposes. Therefore, in some situations, for example, externalconnection terminal 501 may be referred to as a first externalconnection terminal, and external connection terminal 503 may bereferred to as a second external connection terminal. Also, the lamptube may include two end caps respectively coupled to two ends thereof,and the pins may be coupled to the end caps, such that the pins arecoupled to the lamp tube.

FIG. 14E is a block diagram showing components of an LED lamp accordingto an exemplary embodiment. Referring to FIG. 14E, the power supplymodule of the LED lamp includes a rectifying circuit 510, a filteringcircuit 520, and a rectifying circuit 540, and may also include somecomponents of an LED lighting module 530. Rectifying circuit 510 iscoupled to pins 501 and 502 to receive and then rectify an externaldriving signal conducted by pins 501 and 502. Rectifying circuit 540 iscoupled to pins 503 and 504 to receive and then rectify an externaldriving signal conducted by pins 503 and 504. Therefore, the powersupply module of the LED lamp may include two rectifying circuits 510and 540 configured to output a rectified signal at output terminals 511and 512. Filtering circuit 520 is coupled to terminals 511 and 512 toreceive and then filter the rectified signal, so as to output a filteredsignal at output terminals 521 and 522. LED lighting module 530 iscoupled to terminals 521 and 522 to receive the filtered signal andthereby to drive an LED unit (not shown) of LED lighting module 530 toemit light.

The power supply module of the LED lamp in this embodiment of FIG. 14Emay be used in LED tube lamp 500 with a dual-end power supply in FIG.14D. In some embodiments, since the power supply module of the LED lampcomprises rectifying circuits 510 and 540, the power supply module ofthe LED lamp may be used in LED tube lamps 500 with a single-end powersupply in FIGS. 14A and 14B, to receive an external driving signal (suchas the AC supply signal or the AC driving signal described above). Thepower supply module of an LED lamp in this embodiment and otherembodiments herein may also be used with a DC driving signal.

FIG. 15A is a schematic diagram of a rectifying circuit according to anexemplary embodiment. Referring to FIG. 15A, rectifying circuit 610includes rectifying diodes 611, 612, 613, and 614, configured tofull-wave rectify a received signal. Diode 611 has an anode connected tooutput terminal 512, and a cathode connected to pin 502. Diode 612 hasan anode connected to output terminal 512, and a cathode connected topin 501. Diode 613 has an anode connected to pin 502, and a cathodeconnected to output terminal 511. Diode 614 has an anode connected topin 501, and a cathode connected to output terminal 511.

When pins 501 and 502 (generally referred to as terminals) receive an ACsignal, rectifying circuit 610 operates as follows. During the connectedAC signal's positive half cycle, the AC signal is input through pin 501,diode 614, and output terminal 511 in sequence, and later output throughoutput terminal 512, diode 611, and pin 502 in sequence. During theconnected AC signal's negative half cycle, the AC signal is inputthrough pin 502, diode 613, and output terminal 511 in sequence, andlater output through output terminal 512, diode 612, and pin 501 insequence. Therefore, during the connected AC signal's full cycle, thepositive pole of the rectified signal produced by rectifying circuit 610remains at output terminal 511, and the negative pole of the rectifiedsignal remains at output terminal 512. Accordingly, the rectified signalproduced or output by rectifying circuit 610 is a full-wave rectifiedsignal.

When pins 501 and 502 are coupled to a DC power supply to receive a DCsignal, rectifying circuit 610 operates as follows. When pin 501 iscoupled to the anode of the DC supply and pin 502 to the cathode of theDC supply, the DC signal is input through pin 501, diode 614, and outputterminal 511 in sequence, and later output through output terminal 512,diode 611, and pin 502 in sequence. When pin 501 is coupled to thecathode of the DC supply and pin 502 to the anode of the DC supply, theDC signal is input through pin 502, diode 613, and output terminal 511in sequence, and later output through output terminal 512, diode 612,and pin 501 in sequence. Therefore, no matter what the electricalpolarity of the DC signal is between pins 501 and 502, the positive poleof the rectified signal produced by rectifying circuit 610 remains atoutput terminal 511, and the negative pole of the rectified signalremains at output terminal 512.

Therefore, rectifying circuit 610 in this embodiment can output orproduce a proper rectified signal regardless of whether the receivedinput signal is an AC or DC signal.

FIG. 15B is a schematic diagram of a rectifying circuit according to anexemplary embodiment. Referring to FIG. 15B, rectifying circuit 710includes rectifying diodes 711 and 712, configured to half-wave rectifya received signal. Diode 711 has an anode connected to pin 502, and acathode connected to output terminal 511. Diode 712 has an anodeconnected to output terminal 511, and a cathode connected to pin 501.Output terminal 512 may be omitted or grounded depending on actualapplications.

Next, exemplary operation(s) of rectifying circuit 710 is described asfollows.

In one embodiment, during a received AC signal's positive half cycle,the electrical potential at pin 501 is higher than that at pin 502, sodiodes 711 and 712 are both in a cutoff state as being reverse-biased,making rectifying circuit 710 not outputting a rectified signal. Duringa received AC signal's negative half cycle, the electrical potential atpin 501 is lower than that at pin 502, so diodes 711 and 712 are both ina conducting state as being forward-biased, allowing the AC signal to beinput through diode 711 and output terminal 511, and later outputthrough output terminal 512, a ground terminal, or another end of theLED tube lamp not directly connected to rectifying circuit 710.Accordingly, the rectified signal produced or output by rectifyingcircuit 710 is a half-wave rectified signal.

FIG. 15C is a schematic diagram of a rectifying circuit according to anexemplary embodiment. Referring to FIG. 15C, rectifying circuit 810includes a rectifying unit 815 and a terminal adapter circuit 541. Inthis embodiment, rectifying unit 815 comprises a half-wave rectifiercircuit including diodes 811 and 812 and configured to half-waverectify. Diode 811 has an anode connected to an output terminal 512, anda cathode connected to a half-wave node 819. Diode 812 has an anodeconnected to half-wave node 819, and a cathode connected to an outputterminal 511. Terminal adapter circuit 541 is coupled to half-wave node819 and pins 501 and 502, to transmit a signal received at pin 501and/or pin 502 to half-wave node 819. By means of the terminal adaptingfunction of terminal adapter circuit 541, rectifying circuit 810includes two input terminals (connected to pins 501 and 502) and twooutput terminals 511 and 512.

Next, in certain embodiments, rectifying circuit 810 operates asfollows.

During a received AC signal's positive half cycle, the AC signal may beinput through pin 501 or 502, terminal adapter circuit 541, half-wavenode 819, diode 812, and output terminal 511 in sequence, and lateroutput through another end or circuit of the LED tube lamp. During areceived AC signal's negative half cycle, the AC signal may be inputthrough another end or circuit of the LED tube lamp, and later outputthrough output terminal 512, diode 811, half-wave node 819, terminaladapter circuit 541, and pin 501 or 502 in sequence.

Terminal adapter circuit 541 may comprise a resistor, a capacitor, aninductor, or any combination thereof, for performing functions ofvoltage/current regulation or limiting, types of protection,current/voltage regulation, etc. Descriptions of these functions arepresented below.

In practice, rectifying unit 815 and terminal adapter circuit 541 may beinterchanged in position (as shown in FIG. 15D), without altering thefunction of half-wave rectification. FIG. 15D is a schematic diagram ofa rectifying circuit according to an embodiment. Referring to FIG. 15D,diode 811 has an anode connected to pin 502 and diode 812 has a cathodeconnected to pin 501. A cathode of diode 811 and an anode of diode 812are connected to half-wave node 819. Terminal adapter circuit 541 iscoupled to half-wave node 819 and output terminals 511 and 512. During areceived AC signal's positive half cycle, the AC signal may be inputthrough another end or circuit of the LED tube lamp, and later outputthrough output terminal 511 or 512, terminal adapter circuit 541,half-wave node 819, diode 812, and pin 501 in sequence. During areceived AC signal's negative half cycle, the AC signal may be inputthrough pin 502, diode 811, half-wave node 819, terminal adapter circuit541, and output node 511 or 512 in sequence, and later output throughanother end or circuit of the LED tube lamp.

Terminal adapter circuit 541 in embodiments shown in FIGS. 15C and 15Dmay be omitted and is therefore depicted by a dotted line. If terminaladapter circuit 541 of FIG. 15C is omitted, pins 501 and 502 will becoupled to half-wave node 819. If terminal adapter circuit 541 of FIG.15D is omitted, output terminals 511 and 512 will be coupled tohalf-wave node 819.

Rectifying circuit 510 as shown and explained in FIGS. 15A-D canconstitute or be the rectifying circuit 540 shown in FIG. 14E, as havingpins 503 and 504 for conducting instead of pins 501 and 502.

Next, an explanation follows as to choosing embodiments and theircombinations of rectifying circuits 510 and 540, with reference to FIGS.14C and 14E.

Rectifying circuit 510 in embodiments shown in FIG. 14C may comprise,for example, the rectifying circuit 610 in FIG. 15A.

Rectifying circuits 510 and 540 in embodiments shown in FIG. 14E mayeach comprise, for example, any one of the rectifying circuits in FIGS.15A-D, and terminal adapter circuit 541 in FIGS. 15C-D may be omittedwithout altering the rectification function used in an LED tube lamp.When rectifying circuits 510 and 540 each comprise a half-wave rectifiercircuit described in FIGS. 15B-D, during a received AC signal's positiveor negative half cycle, the AC signal may be input from one ofrectifying circuits 510 and 540, and later output from the otherrectifying circuit 510 or 540. Further, when rectifying circuits 510 and540 each comprise the rectifying circuit described in FIG. 15C or 15D,or when they comprise the rectifying circuits in FIGS. 15C and 15Drespectively, only one terminal adapter circuit 541 may be needed forfunctions of voltage/current regulation or limiting, types ofprotection, current/voltage regulation, etc. within rectifying circuits510 and 540, omitting another terminal adapter circuit 541 withinrectifying circuit 510 or 540.

FIG. 16A is a block diagram of a filtering circuit according to anexemplary embodiment. Rectifying circuit 510 is shown in FIG. 16A forillustrating its connection with other components, without intendingfiltering circuit 520 to include rectifying circuit 510. Referring toFIG. 16A, filtering circuit 520 includes a filtering unit 523 coupled torectifying output terminals 511 and 512 to receive, and to filter outripples of a rectified signal from rectifying circuit 510, therebyoutputting a filtered signal whose waveform is smoother than therectified signal. Filtering circuit 520 may further comprise anotherfiltering unit 524 coupled between a rectifying circuit and a pin, whichare for example rectifying circuit 510 and pin 501, rectifying circuit510 and pin 502, rectifying circuit 540 and pin 503, or rectifyingcircuit 540 and pin 504. Filtering unit 524 is for filtering of aspecific frequency, in order to filter out a specific frequencycomponent of an external driving signal. In this embodiment of FIG. 16A,filtering unit 524 is coupled between rectifying circuit 510 and pin501. Filtering circuit 520 may further comprise another filtering unit525 coupled between one of pins 501 and 502 and a diode of rectifyingcircuit 510, or between one of pins 503 and 504 and a diode ofrectifying circuit 540, for reducing or filtering out electromagneticinterference (EMI). In this embodiment, filtering unit 525 is coupledbetween pin 501 and a diode (not shown in FIG. 16A) of rectifyingcircuit 510. Since filtering units 524 and 525 may be present or omitteddepending on actual circumstances of their uses, they are depicted by adotted line in FIG. 16A. Filtering units 523, 524, and 525 may bereferred to herein as filtering sub-circuits of filtering circuit 520,or may be generally referred to as a filtering circuit.

FIG. 16B is a schematic diagram of a filtering unit according to anexemplary embodiment. Referring to FIG. 16B, filtering unit 623 includesa capacitor 625 having an end coupled to output terminal 511 and afiltering output terminal 521 and another end coupled to output terminal512 and a filtering output terminal 522, and is configured to low-passfilter a rectified signal from output terminals 511 and 512, so as tofilter out high-frequency components of the rectified signal and therebyoutput a filtered signal at output terminals 521 and 522.

FIG. 16C is a schematic diagram of a filtering unit according to anexemplary embodiment. Referring to FIG. 16C, filtering unit 723comprises a pi filter circuit including a capacitor 725, an inductor726, and a capacitor 727. As is well known, a pi filter circuit lookslike the symbol rr in its shape or structure. Capacitor 725 has an endconnected to output terminal 511 and coupled to output terminal 521through inductor 726, and has another end connected to output terminals512 and 522. Inductor 726 is coupled between output terminals 511 and521. Capacitor 727 has an end connected to output terminal 521 andcoupled to output terminal 511 through inductor 726, and has another endconnected to output terminals 512 and 522.

As seen between output terminals 511 and 512 and output terminals 521and 522, filtering unit 723 compared to filtering unit 623 in FIG. 16Badditionally has inductor 726 and capacitor 727, which are likecapacitor 725 in performing low-pass filtering. Therefore, filteringunit 723 in this embodiment compared to filtering unit 623 in FIG. 16Bhas a better ability to filter out high-frequency components to output afiltered signal with a smoother waveform.

Inductance values of inductor 726 in the embodiment described above arechosen in some embodiments in the range of about 10 nH to about 10 mH.And capacitance values of capacitors 625, 725, and 727 in theembodiments described above are chosen in some embodiments in the range,for example, of about 100 pF to about 1 uF.

FIG. 17A is a schematic diagram of an LED module according to anexemplary embodiment. Referring to FIG. 17A, LED module 630 has an anodeconnected to the filtering output terminal 521, has a cathode connectedto the filtering output terminal 522, and comprises at least one LEDunit 632. When two or more LED units are included, they are connected inparallel. An anode of each LED unit 632 forms the anode of LED module630 and is connected to output terminal 521, and a cathode of each LEDunit 632 forms the cathode of LED module 630 and is connected to outputterminal 522. Each LED unit 632 includes at least one LED 631. Whenmultiple LEDs 631 are included in an LED unit 632, they are connected inseries, with the anode of the first LED 631 forming the anode of the LEDunit 632 that it is a part of, and the cathode of the first LED 631connected to the next or second LED 631. And the anode of the last LED631 in this LED unit 632 is connected to the cathode of a previous LED631, with the cathode of the last LED 631 forming the cathode of the LEDunit 632 that it is a part of.

In some embodiments, the LED module 630 may produce a current detectionsignal S531 reflecting a magnitude of current through LED module 630 andused for controlling or detecting current on the LED module 630. Asdescribed herein, an LED unit may refer to a single string of LEDsarranged in series, and an LED module may refer to a single LED unit, ora plurality of LED units connected to a same two nodes (e.g., arrangedin parallel). For example, the LED light strip 2 described above may bean LED module and/or LED unit.

FIG. 17B is a schematic diagram of an LED module according to anexemplary embodiment. Referring to FIG. 17B, LED module 630 has an anodeconnected to the filtering output terminal 521, has a cathode connectedto the filtering output terminal 522, and comprises at least two LEDunits 732, with an anode of each LED unit 732 forming the anode of LEDmodule 630, and a cathode of each LED unit 732 forming the cathode ofLED module 630. Each LED unit 732 includes at least two LEDs 731connected in the same way as described in FIG. 17A. For example, theanode of the first LED 731 in an LED unit 732 forms the anode of the LEDunit 732 that it is a part of, the cathode of the first LED 731 isconnected to the anode of the next or second LED 731, and the cathode ofthe last LED 731 forms the cathode of the LED unit 732 that it is a partof. Further, LED units 732 in an LED module 630 are connected to eachother in this embodiment. All of the n-th LEDs 731 respectively of theLED units 732 are connected by every anode of every n-th LED 731 in theLED units 732, and by every cathode of every n-th LED 731, where n is apositive integer. In this way, the LEDs in LED module 630 in thisembodiment are connected in the form of a mesh.

In some embodiments, LED lighting module 530 of the above embodimentsincludes LED module 630, but doesn't include a driving circuit for theLED module 630 (e.g., does not include an LED driving unit for the LEDmodule or LED unit).

Similarly, LED module 630 in this embodiment may produce a currentdetection signal S531 reflecting a magnitude of current through LEDmodule 630 and used for controlling or detecting current on the LEDmodule 630.

FIG. 18 is a block diagram showing components of an LED lamp (e.g., anLED tube lamp) according to an exemplary embodiment. As shown in FIG.18, the power supply module of the LED lamp includes rectifying circuits510 and 540, a filtering circuit 520, and an LED driving circuit 1530,wherein an LED lighting module 530 includes the driving circuit 1530 andan LED module 630. According to the above description in FIG. 14E,driving circuit 1530 in FIG. 18 comprises a DC-to-DC converter circuit,and is coupled to filtering output terminals 521 and 522 to receive afiltered signal and then perform power conversion for converting thefiltered signal into a driving signal at driving output terminals 1521and 1522. The LED module 630 is coupled to driving output terminals 1521and 1522 to receive the driving signal for emitting light. In someembodiments, the current of LED module 630 is stabilized at an objectivecurrent value. Exemplary descriptions of this LED module 630 are thesame as those provided above with reference to FIGS. 17A-17B.

In some embodiments, the rectifying circuit 540 is an optional elementand therefore can be omitted, so it is depicted in a dotted line in FIG.18. Therefore, the power supply module of the LED lamp in thisembodiment can be used with a single-end power supply coupled to one endof the LED lamp, and can be used with a dual-end power supply coupled totwo ends of the LED lamp. With a single-end power supply, examples ofthe LED lamp include an LED light bulb, a personal area light (PAL),etc.

FIG. 19A is a block diagram of an LED lamp according to an exemplaryembodiment. Compared to FIG. 18, the embodiment of FIG. 19A includesrectifying circuits 510 and 540, and a filtering circuit 520, andfurther includes an anti-flickering circuit 550; wherein the powersupply module may also include some components of an LED lighting module530. The anti-flickering circuit 550 is coupled between filteringcircuit 520 and LED lighting module 530. It's noted that rectifyingcircuit 540 may be omitted, as is depicted by the dotted line in FIG.19A.

Anti-flickering circuit 550 is coupled to filtering output terminals 521and 522, to receive a filtered signal, and under specific circumstancesto consume partial energy of the filtered signal so as to reduce (theincidence of) ripples of the filtered signal disrupting or interruptingthe light emission of the LED lighting module 530. In general, filteringcircuit 520 has such filtering components as resistor(s) and/orinductor(s), and/or parasitic capacitors and inductors, which may formresonant circuits. Upon breakoff or stop of an AC power signal, as whenthe power supply of the LED lamp is turned off by a user, theamplitude(s) of resonant signals in the resonant circuits will decreasewith time. But LEDs in the LED module of the LED lamp are unidirectionalconduction devices and require a minimum conduction voltage for the LEDmodule. When a resonant signal's trough value is lower than the minimumconduction voltage of the LED module, but its peak value is still higherthan the minimum conduction voltage, the flickering phenomenon willoccur in light emission of the LED module. In this case anti-flickeringcircuit 550 works by allowing a current matching a defined flickeringcurrent value of the LED component to flow through, consuming partialenergy of the filtered signal which should be higher than the energydifference of the resonant signal between its peak and trough values, soas to reduce the flickering phenomenon. In certain embodiments, theanti-flickering circuit 550 may operate when the filtered signal'svoltage approaches (and is still higher than) the minimum conductionvoltage.

In some embodiments, the anti-flickering circuit 550 may be moresuitable for the situation in which LED lighting module 530 doesn'tinclude driving circuit 1530, for example, when LED module 630 of LEDlighting module 530 is (directly) driven to emit light by a filteredsignal from a filtering circuit. In this case, the light emission of LEDmodule 630 will directly reflect variation in the filtered signal due toits ripples. In this situation, the introduction of anti-flickeringcircuit 550 will prevent the flickering phenomenon from occurring in theLED lamp upon the breakoff of power supply to the LED lamp.

FIG. 19B is a schematic diagram of the anti-flickering circuit accordingto an exemplary embodiment. Referring to FIG. 19B, anti-flickeringcircuit 650 includes at least a resistor, such as two resistorsconnected in series between filtering output terminals 521 and 522. Inthis embodiment, anti-flickering circuit 650 in use consumes partialenergy of a filtered signal continually. When in normal operation of theLED lamp, this partial energy is far lower than the energy consumed byLED lighting module 530. But upon a breakoff or stop of the powersupply, when the voltage level of the filtered signal decreases toapproach the minimum conduction voltage of LED module 630, this partialenergy is still consumed by anti-flickering circuit 650 in order tooffset the impact of the resonant signals which may cause the flickeringof light emission of LED module 630. In some embodiments, a currentequal to or larger than an anti-flickering current level may be set toflow through anti-flickering circuit 650 when LED module 630 is suppliedby the minimum conduction voltage, and then an equivalentanti-flickering resistance of anti-flickering circuit 650 can bedetermined based on the set current.

FIG. 20A is a block diagram of an LED lamp according to an exemplaryembodiment. Compared to FIG. 18, the embodiment of FIG. 20A includesrectifying circuits 510 and 540, a filtering circuit 520, and a drivingcircuit 1530, and further includes a mode switching circuit 580; whereinan LED lighting module 530 is composed of driving circuit 1530 and anLED module 630. Mode switching circuit 580 is coupled to at least one offiltering output terminals 521 and 522 and at least one of drivingoutput terminals 1521 and 1522, for determining whether to perform afirst driving mode or a second driving mode, as according to a frequencyof the external driving signal. In the first driving mode, a filteredsignal from filtering circuit 520 is input into driving circuit 1530,while in the second driving mode the filtered signal bypasses at least acomponent of driving circuit 1530, making driving circuit 1530 stopworking in conducting the filtered signal, allowing the filtered signalto (directly) reach and drive LED module 630. The bypassed component(s)of driving circuit 1530 may include an inductor or a switch, which whenbypassed makes driving circuit 1530 unable to transfer and/or convertpower, and then stop working in conducting the filtered signal. Ifdriving circuit 1530 includes a capacitor, the capacitor can still beused to filter out ripples of the filtered signal in order to stabilizethe voltage across the LED module. When mode switching circuit 580determines to perform the first driving mode, allowing the filteredsignal to be input to driving circuit 1530, driving circuit 1530 thentransforms the filtered signal into a driving signal for driving LEDmodule 630 to emit light. On the other hand, when mode switching circuit580 determines to perform the second driving mode, allowing the filteredsignal to bypass driving circuit 1530 to reach LED module 630, filteringcircuit 520 then becomes in effect a driving circuit for LED module 630.Then filtering circuit 520 provides the filtered signal as a drivingsignal for the LED module for driving the LED module to emit light.

In some embodiments, the mode switching circuit 580 can determinewhether to perform the first driving mode or the second driving modebased on a user's instruction or a detected signal received by the LEDlamp through pins 501, 502, 503, and 504. In some embodiments, a modedetermination circuit 590 is used to determine the first driving mode orthe second driving mode based on a signal received by the LED lamp andso the mode switching circuit 580 can determine whether to perform thefirst driving mode or the second driving mode based on a determinedresult signal S580 or/and S585. With the mode switching circuit, thepower supply module of the LED lamp can adapt to or perform one ofappropriate driving modes corresponding to different applicationenvironments or driving systems, thus improving the compatibility of theLED lamp. In some embodiments, rectifying circuit 540 may be omitted, asis depicted by the dotted line in FIG. 20A.

FIG. 20B is a schematic diagram of a mode determination circuit in anLED lamp according to an exemplary embodiment. Referring to FIG. 20B,the mode determination circuit 690 comprises a symmetrical trigger diode691 and a resistor 692, configured to detect a voltage level of anexternal driving signal. The symmetrical trigger diode 691 and theresistor 692 are connected in series; and namely, one end of thesymmetrical trigger diode 691 is coupled to the first filtering outputterminal 521, the other end thereof is coupled to one end of theresistor 692, and the other end of the resistor 692 is coupled to thesecond filtering output terminal 522. A connection node of thesymmetrical trigger diode 691 and the resistor 692 generates adetermined result signal S580 transmitted to a mode switching circuit.When an external driving signal is a signal with high frequency and highvoltage, the determined result signal S580 is at a high voltage level tomake the mode switching circuit determine to operate at the seconddriving mode. For example, when the lamp driving circuit 505, as shownin FIG. 14A and FIG. 14D, exists, the lamp driving circuit 505 convertsthe AC power signal of the AC power supply 508 into an AC driving signalwith high frequency and high voltage, transmitted into the LED tube lamp500. At this time, the mode switching circuit determines to operate atthe second driving mode and so the filtered signal, outputted by a firstfiltering output terminal 521 and a second filtering output terminal522, directly drive the LED module 630 to light. When the externaldriving signal is a signal with low frequency and low voltage, thedetermined result signal S580 is at a low voltage level to make the modeswitching circuit determine to operate at the first driving mode. Forexample, when the lamp driving circuit 505, as shown in FIG. 14A andFIG. 14D, does not exist, the AC power signal of the AC power supply 508is directly transmitted into the LED tube lamp 500. At this time, themode switching circuit determines to operate at the first driving modeand so the filtered signal, outputted by the first filtering outputterminal 521 and the second filtering output terminal 522, is convertedinto an appropriate voltage level to drive the LED module 630 to light.

In some embodiments, a breakover voltage of the symmetrical triggerdiode 691 is in a range of 400V˜1300V, in some embodiments morespecifically in a range of 450V˜700V, and in some embodiments morespecifically in a range of 500V˜600V.

The mode determination circuit 690 may include a resistor 693 and aswitch 694. The resistor 693 and the switch 694 could be omitted basedon the practice application, thus the resistor 693 and the switch 694and a connection line thereof are depicted in a dotted line in FIG. 20B.The resistor 693 and the switch 694 are connected in series; namely oneend of the resistor 693 is coupled to the first filtering outputterminal 521, the other end is coupled to one end of the switch 694, andanother end of the switch 694 is coupled to a second filtering outputterminal 522. A control end of the switch 694 is coupled to theconnection node of the symmetrical trigger diode 691 and the resistor692 for receiving the determined result signal S580. Accordingly, aconnection node of the resistor 693 and the switch 694 generates anotherdetermined result signal S585. The determined result signal S585 is aninverted signal of the determined result signal S580 and so they couldbe applied to a mode switching circuit having switches for switchingbetween two modes.

FIG. 20C is a schematic diagram of a mode determination circuit in anLED lamp according to an exemplary embodiment. Referring to FIG. 20C,the mode determination circuit 790 includes a capacitor 791, resistors792 and 793, and a switch 794. The capacitor 791 and the resistor 792are connected in series as a frequency determination circuit 795 fordetecting a frequency of an external driving signal. One end of thecapacitor 792 is coupled to a first rectifying output terminal 511, theother end is coupled to one end of the resistor 791, and the other endof the resistor 791 is coupled to a second rectifying output terminal512. The frequency determination circuit 795 generates the determinedresult signal S580 at a connection node of the resistor 791 and thecapacitor 792. A voltage level of the determined result signal S580 isdetermined based on the frequency of the external driving signal. Insome embodiments, the higher the frequency of the external drivingsignal is, the higher the voltage level of the determined result signalS580 is, and the lower the frequency of the external driving signal is,the lower the voltage level of the determined result signal S580 is.Hence, when the external driving signal is a higher frequency signal(e.g., more than 20 KHz) and high voltage, the determined result signalS580 is at high voltage level to make the mode switching circuitdetermine to operate at second driving mode. When the external drivingsignal is a lower frequency signal and low voltage signal, thedetermined result signal S580 is at a low voltage level to make the modeswitching circuit determine to operate at first driving mode. Similarly,in some embodiments, the mode determination circuit 790 may include aresistor 793 and a switch 794. The resistor 793 and the switch 794 areconnected in series between the first filtering output terminal 521 andthe second filtering output terminal 522, and a control end of theswitch 794 is coupled to the frequency determination circuit 795 toreceive the determined result signal S580. Accordingly, anotherdetermined result signal S585 is generated at a connection node of theresistor 793 and the switch 794 and is an inverted signal of thedetermined result signal S580. The determined result signals S580 andS585 may be applied to a mode switching circuit having two switches. Theresistor 793 and the switch 794 could be omitted based on practiceapplication and so are depicted in a dotted line

FIG. 21A is a schematic diagram of a mode determination circuitaccording to some exemplary embodiments. FIG. 21B is a schematic diagramof an LED tube lamp including the exemplary mode determination circuitof FIG. 21A according to some exemplary embodiments. Referring to FIGS.21A and 21B, mode determination circuit 2010 may be coupled to arectifying circuit (e.g., the rectifying circuit 510 as illustrated inthe previous figures), for receiving a rectified signal. In thisexemplary embodiment, the mode determination circuit 2010 has twofunctions of allowing a continual current to flow through the LED unit632 and regulating the continuity of current to flow through the LEDunit 632. The mode determination circuit 2010 detects a state of aproperty of the rectified signal and selectively determines whether toperform a first mode or a second mode of lighting operation according tothe state of the property of the rectified signal. When performing thefirst mode of lighting operation, the mode determination circuit 2010allows a continual current, which in some embodiments may be acontinuous current without cessation, to flow through the LED unit 632until the external driving signal is disconnected from the LED tubelamp. When performing the second mode of lighting, the modedetermination circuit 2010 regulates the continuity of current to flowthrough the LED unit 632, for example by allowing a discontinuouscurrent to flow through the LED unit 632.

The mode determination circuit 2010 includes a first voltage divider201, a second voltage divider 202, a resistor 2019, a capacitor 2020 anda control circuit 2018. The first voltage divider 201 includes a firstresistor depicted in FIGS. 21A and 21B as resistor 2012, and a secondresistor depicted in FIGS. 21A and 21B as resistor 2013. The resistor2012 is connected to the resistor 2013 between the first output terminal511 and the second output terminal 512. For example, one end of thefirst resistor 2012 is connected to a connection node C to which thefirst output terminal 511 is connected and the opposite end of the firstresistor 2012 is connected to a connection node D to which one end ofthe second resistor 2013 is connected. In some embodiments, the oppositeend of the second resistor 2013 is connected to the second outputterminal 512 via at least a diode 2022 included in the first voltagedivider 201, but the disclosure is not limited thereto. In someembodiments, the opposite end of the second resistor 2013 may bedirectly connected to the second output terminal 512. The second voltagedivider 202 includes a third resistor depicted in FIGS. 21A and 21B asresistor 2014, and a fourth resistor depicted in FIGS. 21A and 21B asresistor 2015. The resistor 2014 is connected to the resistor 2015between the first output terminal 511 and the second output terminal512. For example, one end of the third resistor 2014 is connected to aconnection node C to which the first output terminal 511 is connectedand the opposite end of the third resistor 2014 is connected to aconnection node E to which one end of the fourth resistor 2015 isconnected. In some embodiments, the opposite end of the fourth resistor2015 is directly connected to the second output terminal 512. Thecontrol circuit 2018 is coupled between the first voltage divider 201and the LED unit 632, and the control circuit 2018 is also coupledbetween the second voltage divider 202 and the LED unit 632.

Referring to FIGS. 21A and 21B, in some embodiments, the modedetermination circuit may not be coupled to a rectifying circuit. Thus,when the mode determination circuit 2010 is not coupled with arectifying circuit, the mode determination circuit 2010 may detect astate of a property of the external driving signal (e.g., unrectifiedexternal driving signal) and selectively determines whether to perform afirst mode or a second mode of lighting operation according to the stateof the property of the external driving signal. When performing thefirst mode of lighting operation, the mode determination circuit 2010allows a continual current, which in some embodiments may be acontinuous current without cessation, to flow through the LED unit 632until the external driving signal is disconnected from the LED tube lampor a current generated from the input external driving signal is stoppedfrom passing through the LED unit 632 as a result of any intended orunintended operation(s) of the LED tube lamp. When performing the secondmode of lighting, the mode determination circuit 2010 regulates thecontinuity of current to flow through the LED unit 632, for example byallowing a discontinuous current to flow through the LED unit 632.

In some embodiments, the control circuit 2018 may be any circuit thathas a function of controlling, for instance, a CPU or a MCU. The controlcircuit 2018 in this embodiment is an IC module having an input terminalVCC, an input terminal STP, an input terminal CS, an output terminal2011 and an output terminal 2021. The input terminal VCC is connected toa connection node between the resistor 2019 and the capacitor 2020 forobtaining power from the rectifying circuit 510 for operation of the ICmodule. The output terminal 2011 is connected to a reference voltagesuch as the ground potential. The other output terminal 2021 is coupledto the LED unit 632. The first voltage divider 201 is configured forreceiving the rectified signal from the rectifying circuit 510 toproduce a first fraction voltage of the rectified signal at a connectionnode D between the first resistor 2012 and the second resistor 2013. Theinput terminal STP is connected to the connection node D. The controlcircuit 2018 receives the first fraction voltage at the terminal STP anddetermines whether to perform the first mode of lighting operationaccording to the first fraction voltage. In the first mode of lightingoperation, the control circuit 2018 provides a continuous current at theoutput terminal 202 to allow the continual current to flow through theLED unit 632. The second voltage divider 202 is used for receiving therectified signal from the rectifying circuit 510 to produce a secondfraction voltage of the rectified signal at a connection node E betweenthe third resistor 2014 and the fourth resistor 2015. The input terminalCS is connected to the connection node E. The control circuit 2018receives the second fraction voltage at the input terminal CS anddetermines whether to perform the second mode of lighting operationaccording to the second fraction voltage. In the second mode of lightingoperation, the control circuit 2018 provides a discontinuous current toregulate the continuity of the current to the LED unit 632.

In some embodiments, the control circuit 2018 includes a switchingcircuit 2024. The switching circuit 2024 is connected to the outputterminals 2011 and 2021 of the control circuit 2018 to achieve thefunctions of allowing the continual current to flow through the LED unit632 and regulating the continuity of current to flow through the LEDunit 632. When performing the first mode of lighting operation, thecontrol circuit 2018 allows the continuous current to flow through theLED unit 632 by continuously turning on, or maintaining an on state of,the switching circuit 2024. When performing the second mode of lightingoperation, the control circuit 2018 allows the discontinuous current toflow through the LED unit 632 by alternately turning on and off theswitching circuit 2024. The first mode of lighting operation may also bereferred to as continuous-conduction-mode (CCM) in which the current inan energy transfer circuit (which typically comprises inductor(s) and/orresistor(s)) connected to the LED unit 632 does not go to zero betweenswitching cycles of the switching circuit 2024. The second mode oflighting operation may also be referred to asdiscontinuous-conduction-mode (DCM) in which the current goes to zeroduring part of the switching cycle of the switching circuit 2014.

The switching circuit 2024 may include an electronic switch such as atransistor. The transistor may be a MOSFET, wherein the source terminalof the MOSFET is connected to the terminal 2011 to connect to areference voltage such as the ground potential, and the drain terminalof the MOSFET is connected to the terminal 2021 to couple to the LEDunit 632. Accordingly, in the first mode of lighting, the controlcircuit 2018 allows the continuous current to flow to the LED unit 632by continuously turning on, or maintaining an on state of, the MOSFET,and in the second mode of lighting, the control circuit 2018 allows thediscontinuous current to flow to the LED unit 632 by alternately turningon and off the MOSFET.

In some embodiments, the switching circuit 2024 may be a component ofthe LED tube lamp not included in control circuit 2018. If the LED tubelamp further includes the switching circuit 2024, the switching circuit2024 is coupled between the control circuit 2018 and the LED unit 632.

Accordingly, upon the LED lighting tube lamp being supplied by anelectrical ballast, the control circuit 2018 receives the first fractionvoltage at the terminal STP and determines whether the first fractionvoltage is in the first voltage range. If the first fraction voltage isin the first voltage range, the control circuit 2018 continuously turnson the switching circuit 2024 to allow a continuous current to flowthrough the LED unit 632 to perform the first mode of lighting. Inaddition, the control circuit 2018 receives the second fraction voltageat the terminal CS and determines whether the second fraction voltage isin the second voltage range. If the second fraction voltage is in thesecond voltage range, the control circuit 2018 alternately turns on andoff the switching circuit 2024 to allow the discontinuous current toflow through the LED unit 632 to perform the second mode of lighting.The control circuit 2018 performs the first mode and second mode oflighting until the external driving signal is disconnected from the LEDtube lamp. Once the LED tube lamp is started again, the control circuit2018 determines again whether to perform the first mode or the secondmode according to the first fraction voltage and the second fractionvoltage of the rectified signal.

In some embodiments, the first voltage range is defined to encompassvalues less than a first voltage value or larger than a second voltagevalue which is larger than the first voltage value. Thus, the controlcircuit 2018 performs the first mode of lighting if the first fractionvoltage is greater than the second voltage value or less than the firstvoltage value. For example, the first mode of lighting may comprise twofirst modes of lighting operations, and the control circuit 2018performs one of the two first modes of lighting operation when theexternal driving signal is provided by an electronic ballast to the STPterminal of the control circuit 2018. When the external signal isprovided by an electronic ballast to the STP terminal of the controlcircuit 2018, a voltage level at the STP terminal is larger than thesecond voltage value which is larger than the first voltage value. Thecontrol circuit 2018 performs the other of the two first modes oflighting operation when the external driving signal is provided by aninductive ballast to the STP terminal of the control circuit 2018. Whenthe external signal is provided by an inductive ballast to the STPterminal of the control circuit 2018, a voltage level at the STPterminal is less than the first voltage value. The first voltage valuemay be in some embodiments between 0 V and 0.5 V, and may be in someembodiments between 0 V and 0.1 V, and may be in some embodiments 0.1 V.The second voltage value is in some embodiments 1 V, and may be in someembodiments 1.2 V. The second voltage range is defined to encompassvalues larger than a third voltage value and less than a fourth voltagevalue which is larger than the third voltage value. The third voltagevalue may be in some embodiments between 0.5 V and 0.85 V, and may be insome embodiments between 0.7 V and 0.8 V, and may be in some embodimentsbetween 0.85 V and 1.0 V, and may be in some embodiments between 0.9 Vand 0.98 V, and may be 0.95 V in some embodiments.

In some embodiments, the LED tube lamp further includes an RC circuit203. The RC circuit 203 includes a resistor 2016 and a capacitor 2017. Afirst end of the resistor 2016 is connected to the connection node E. Asecond end of the resistor 2016 is connected to a first end of thecapacitor 2017 and the input terminal CS of the control circuit 2018. Asecond end of the capacitor 2017 is connected to the second outputterminal 512 of the rectifying circuit 510. The RC circuit 203 isconfigured to receive the second fraction voltage at node E. When thesecond fraction voltage is in the second voltage range, the capacitor2017 is charged and discharged repeatedly to produce a voltage variationat the first end of the capacitor 2017 to alternately turn on and offthe switching circuit 2024 to allow the discontinuous current to flowthrough the LED unit 632. Resistance value of resistor 2016 may bebetween 0.5 K and 4K ohms, and may be in some embodiments between 1 Kand 3 K ohms, and may be in some embodiments 1K. Capacitance value ofthe capacitor 2017 may be in some embodiments between 1 nF and 500 nF,and may be in some embodiments between 20 nF and 30 nF, and may be insome embodiments 4.7 nF.

In some embodiments, the RC circuit 203 may be disposed with the secondvoltage divider 202. That is, the second voltage divider 202 includesthe resistors 2014 and 2015 and further includes the resistor 2016 andthe capacitor 2017. In other embodiments, the RC circuit 203 may be acomponent of the control circuit 2018. For example, the control circuit2018 may include the IC module and further may include the resistor 2016and the capacitor 2017. In this embodiment, the first end of thecapacitor 2017 is connected to the switching circuit 2024 to control theswitching circuit 2024.

Furthermore, in some embodiments, the RC circuit 203 may be replaced bya pulse width modulation circuit. The pulse width modulation circuit iscoupled between the switching circuit 2024 and the connection node E.The pulse width modulation circuit is configured to receive the secondfraction voltage and then produce a pulse signal with a duty-cycleresponsive to the second fraction voltage, and the pulse signal is usedto alternately turning on and off the switching circuit 2024 to allowthe discontinuous current to flow to the LED unit 632.

In applications, when a first type of electronic ballast is applied,during the starting period (less than 100 ms, typically between about20-30 ms) of the LED tube lamp, the voltage at node C may be between200-300V, then the voltage at the node C rises when the ballast operatesin steady state, causing the first fraction voltage at node D rise. Whenthe second fraction voltage reaches the first voltage range, theswitching circuit 2024 is turned on and being kept in conduction state.In this situation, a constant current is provided to the LED unit 632.In some embodiments, resistance values of resistors 2012 and 2013 may be540 K ohms and 1 K ohms, respectively.

Similarly, when a second type of the electronic ballast is applied,during the starting period, the second fraction voltage at node E mayrise to reach the second voltage range when the electronic ballastoperates in steady state. Then the switching circuit 2024 is alternatelyturned on and off by the RC circuit 203 or the pulse width modulationcircuit. In this situation, a discontinuous current is provided to theLED unit 632. In some embodiments, resistance values of resistors 2014and 2015 may be 420 K ohms and 1 K ohms, respectively.

When an inductive ballast is applied, the characteristic of theinductive ballast is that its current or voltage periodically crosseszero value as the current or voltage signal proceeds with time. Duringthe starting period of the LED tube lamp powered by the commercialpower, the first fraction voltage produced by the first voltage divider201 may be less than the first voltage value which facilitates theswitching circuit 2024 to be turned on and maintain a conducting state.Therefore, the control circuit 2018 allows a constant current to flow tothe LED unit 632.

In some embodiments, the mode determination circuit 2010 comprises aballast interface circuit as an interface between the LED tube lamp andan electrical ballast used to supply the LED tube lamp. Accordingly, TheLED tube lamp can be applied to or be supplied by each of an electronicballast or an inductive ballast.

In addition, the mode determination circuit 2010 has another function ofbeing open-circuit for a period during the initial stage of starting theLED tube lamp for preventing the energy of the AC driving signal fromreaching the LED module 630. The mode determination circuit 2010 willnot enter a conduction state until a period of delay passes. The periodof delay may be a defined as a delay which is between about 10milliseconds and about 1 second.

In some embodiments, the LED tube lamp may include essentially nocurrent-limiting capacitor coupled in series to the LED unit 632. Forexample, an equivalent current-limiting capacitance coupled in series tothe LED unit 632 may be below about 0.1 nF.

In some embodiments, in order to stabilize the voltage at the node D,the mode determination circuit 2010 may further comprise a capacitorconnected in parallel with the resistor 2013. The capacitance of thecapacitor may be in some embodiments between 100 nF and 500 nF, and maybe in some embodiments between 200 nF to 300 nF, and may be in someembodiments 220 nF.

In some embodiments, the mode determination circuit 2010 may furthercomprises at least a diode 2022 coupled between the first voltagedivider 201 and the second output terminal 502. The voltage drop of thediode 2022 when electrically conducting is larger than the first voltagevalue. Thereby, the voltage level at node D is always larger than thefirst voltage value, such that the mode determination circuit 2010always performs the first mode of lighting with the first fractionvoltage higher than the second voltage value.

In some embodiments, in order to increase a voltage rating of the ICmodule, the mode determination circuit 2010 may further include adischarge tube 2023. Two ends of the discharge tube 2023 are connectedto the output terminal 2021 and the ground potential respectively. Avoltage rating of the discharge tube 2023 in some embodiments may bebetween 300 V and 600 V, and may be in some embodiments between 400 Vand 500V, and may be in some embodiments 400 V. In some embodiments, thedischarge tube 2023 also may be replaced by a thyristor.

In some embodiments, the property of the rectified signal may be thefrequency level or voltage level of the rectified signal. For example, afrequency detection circuit or other voltage detection circuits can beused to replace the voltage divider(s). Thus, the mode determinationcircuit 2010 can detect the voltage level or frequency level of therectified signal to determine whether to perform the first mode and thesecond mode of lighting.

Referring to FIG. 21B again, in order to reduce a pulse current resultfrom electrical ballasts, the LED tube lamp may further include a noisesuppressing circuit 570 coupled between the mode determination circuit2010 and the LED unit 632, and the noise suppressing circuit 570 isconnected in series with the LED unit 632. In some embodiments, thenoise-suppressing circuit 570 is an optional element and therefore maybe omitted. In one embodiment, if noise-suppressing circuit 570 isomitted, one end (i.e., the cathode as depicted in FIG. 21B) of LED unit632 is directly connected to the output terminal 2021 of the modedetermination circuit 2010.

In some embodiments, the noise suppressing circuit 570 includes aninductor 571 connected to the cathode of the LED unit 632 between theLED unit 632 and the output terminal 2021 of the mode determinationcircuit 2010 for reducing an abrupt change in the current provided tothe LED unit 632. However, a current flowing through the inductor 571may be larger than a current threshold, for instance, 0.35 A. Therefore,an over-current may be generated and the inductor 571 may be overheateddue to the generation of the overcurrent. In order to eliminate theovercurrent, noise suppressing circuit 570 may further include aresistor 573, a resistor 574 and a transistor 575 to form anover-current protection circuit. The first terminal of the transistor575 is connected to a connection node between the LED unit 632 and theinductor 571 to connect to the first end of the inductor 571 to thecathode of the LED unit 632, the second terminal of the transistor 575(e.g., the gate terminal of the transistor 575) is connected to thesecond end of the inductor 571, and the third terminal of the transistor575 is coupled to the output terminal 2021 of the mode determinationcircuit 2010. The resistor 574 is connected between the third terminaland the second terminal of the transistor 575. The resistor 573 isconnected between the first terminal and the second terminal of thetransistor 575.

The over-current protection circuit will be triggered when the currentflowing through the inductor 571 is larger than a predefined currentthreshold. In general, the current from the LED unit 632 flows throughthe inductor 571 and resistor 574 thereby incurring a voltage dropacross the resistor 574. So, if the current increases, the voltage dropmay increase to reach a conducting voltage (e.g. 0.7 V) of thetransistor 575 thereby to turn on the transistor 575 to conduct current.Accordingly, when the transistor 575 operates in a conducting state, theconducting state of the transistor 575 diverts some current from flowingthrough the inductor 571 thus achieving the purpose of preventingexcessive current from flowing through the inductor 571. The transistor575 may comprise a BJT or a MOSFET. In some embodiments, the inductor571 may be connected in parallel with the anti-flickering circuit 550and 650 as depicted in FIGS. 19A and 19B, respectively. In someembodiments, inductance value of the inductor 571 may be between 1 mHand 10 mH, and may be in some embodiments between 1 mH and 8 mH, and maybe in some embodiments 6 mH.

In some embodiments, the noise-suppressing circuit 570 may furtherinclude a freewheel diode 572 for providing a current path. The cathodeof the freewheel diode 572 is connected to the cathode of the LED unit632 and the anode of the freewheel diode 572 is connected to the secondterminal (e.g., the gate terminal) of the transistor 575. A portion ofthe current flowing through the inductor 571 flows through the freewheeldiode 572.

In some embodiments, the freewheel diode 572, resistor 573, resistor 574and transistor 575 are optional elements and therefore can be omitted.In one embodiment, if freewheel diode 572, resistor 573, resistor 574and transistor 575 are omitted, the second end of the inductor 571 isdirectly connected to the output terminal 2021 of the mode determinationcircuit 2010.

In some embodiments, noise-suppressing circuit 570 may be connectedbetween a rectifying circuit 510 and the LED unit 632. In such cases,the function of the noise-suppressing circuit 570 will not be affected.

In some embodiments, the filtering circuit 520 may be coupled betweenthe mode determination circuit 2010 and the LED unit 632, and capacitor625 can be a component of the filtering circuit 520.

In various embodiments, the mode determination circuit 2010 may bereferred to as a ballast interface circuit. The ballast interfacecircuit may also be coupled to the first external connection terminaland the second external connection terminal between the lamp drivingcircuit 505 such as an electrical ballast and the LED unit 632 forreceiving an external driving signal from the electrical ballast fortransmitting power from the electrical ballast to the LED unit 632. Insome embodiments, the ballast interface circuit includes a detectingcircuit and a control circuit coupled to the detecting circuit. Thedetecting circuit detects a state of a property of the external drivingsignal. In some embodiments, the property of the external driving signalis the voltage level of the external driving signal. The detectingcircuit includes the first voltage divider 201 and the second voltagedivider 202 in FIG. 21A for receiving the external driving signal toobtain a first fraction voltage of the external driving signal and asecond fraction voltage of the external driving signal. The detectingcircuit determines whether the first fraction voltage is in the firstvoltage range, and determines whether the second fraction voltage is inthe second voltage range. According to the voltage level of externaldriving signal, the control circuit selectively determines to perform afirst mode or a second mode of lighting. When performing the first modeof lighting, the control circuit allows continual current to flowthrough the LED unit 632 until the external driving signal isdisconnected from the LED tube lamp; and when performing the second modeof lighting, the control circuit regulates the continuity of current toflow through the LED unit 632.

In other embodiments, the property of the external driving signal may bethe frequency level of the external driving signal. In variousembodiments, a frequency detection circuit or other voltage detectioncircuits can be used to replace the first voltage divider 201 and thesecond voltage divider 202. Accordingly, the ballast interface circuitcan detect the voltage level or the frequency level of the externaldriving signal to determine whether to perform the first mode and thesecond mode of lighting.

FIG. 21C is a schematic diagram of an LED tube lamp according to someembodiments, which includes an embodiment of the mode determinationcircuit 2010 of FIG. 21A. Compared to that shown in FIG. 21B, thepresent embodiment comprises the rectifying circuits 510 and 540, thecapacitor 625, the noise suppressing circuit 570, and the LED unit 632,and further includes two filament-simulating circuits 1760. Thefilament-simulating circuits 1760 are respectively coupled between thepins 501 and 502 and coupled between the pins 503 and 504. Thefilament-simulating circuit 1760 includes capacitors 1763 and 1764, andthe resistors 1765 and 1766. The capacitors 1763 and 1764 are connectedin series and coupled between the pins 503 and 504 and coupled betweenthe pins 501 and 502. The resistors 1765 and 1766 are connected inseries and coupled between the pins 503 and 504 and coupled between thepins 501 and 502. Furthermore, the connection node between thecapacitors 1763 and 1764 is coupled to that of the resistors 1765 and1766. Accordingly, the LED tube lamp in this embodiment can be appliedto or be supplied by programmed-start ballasts. When a programmed-startballast is applied, in a process of preheating, an AC current flowsthrough the capacitors 1763 and 1764 and resistors 1765 and 1766 toachieve the function of simulating the operation of actual filaments.Accordingly, the LED tube lamp is compatible with the programmed-startballast. That is, the programmed-start ballast can successfully startthe LED tube lamp in the embodiments.

Resistance values of resistors 1766 and 1765 may be between 10 K and 1 Mohms, and may be in some embodiments between 100 K and 1 M ohms, and maybe in some embodiments 100 K. Capacitance values of the capacitors 1763and 1764 may be in some embodiments between 3 nF and 2 pF, and may be insome embodiments 3 nF and 100 nF, and may be in some embodiments 4.7 nF.

In some embodiments, resistors 1766 and 1765 may be resistors withnegative temperature coefficient. If the filament-simulating circuits1760 includes resistors 1766 and 1765 with negative temperaturecoefficient, resistance value of the resistors 1766 and 1765 may be nogreater than 15 ohms, and may be in some embodiments between 2 to 10ohms, and may be in some embodiments between 4 ohms and 5 ohms.

In applications, with reference back to FIGS. 7 and 8, the filteringcircuit 520, one of the filament-simulating circuits 1760, therectifying circuit 510, anti-flickering circuit 550 and 650, and the LEDmodule 630 may be disposed on the long circuit sheet 251 of the LEDlight strip 2. The mode determination circuit 2010, anotherfilament-simulating circuit 1760, noise suppressing circuit 570, and therectifying circuit 540 may be disposed on the short circuit board 253.In some embodiments, if filtering circuit 520 includes the capacitor625, the capacitor 625 may be implemented by two film capacitorsconnected to each other and to be disposed on the long circuit sheet 251of the LED light strip 2. In some embodiments, both of thefilament-simulating circuits 1760 may be disposed on the short circuitboard 253 together. In one embodiment, the inductance 571 may bedisposed on the short circuit board 253 if the inductance value of theinductor 571 is 6 mH. This 6-mh inductor is too heavy to dispose on thelong circuit sheet 251 due to the difficulty of the manufacturing of thelong circuit sheet 251 with bendable structure.

With reference back to FIG. 6, welding defects may exist between thesoldering pads “a” of power supply 5 and soldering pads “b” of the LEDlight strip 2. Welding defects may block the intended current pathbetween the power supply 5 and the LED light strip 2 (which light strip2 may comprise a flexible printed circuit board (FPC)) after supplyingpower, such that a high voltage (typically 600 V) exists between ananode electrode and cathode electrode of the power supply 5, or betweena anode electrode and a cathode electrode of the LED unit 632 on the LEDlight strip 2. Such high voltage causes the LED module 630 having one ormore LED unit 632 damages from sparkling or arcing.

To prevent (the effects caused by) arcing and sparkling, the LED tubelamp may include a discharge device 620. The discharge device 620 isdisposed on the circuit board and configured to connect in parallel withthe LED unit 632 (i.e., connected between anode and cathode electrodesof the LED unit 632) on the LED light strip 2. In a case that power issupplied normally, the LED 631 limits the voltage between the anode andcathode electrodes of the LED unit 632. Under such circumstances, thevoltage across the LED unit 632 may be less than 200 V. But, if weldingdefects exist, after the LED tube lamp is supplied by power, aninstantaneously high (e.g., larger than a predefined threshold voltage)voltage may occur across the anode and cathode electrodes of the LEDunit 632. Then, the discharge device 620 can discharge electricity toserve to prevent the instantaneously high voltage across the LED unit632 from being larger than the predefined threshold voltage. Thedischarge device 620 thus protects the LED unit 632 against arcing orsparkling due to the instantaneously high voltage across the LED unit632. In some embodiments, the discharge device 620 may be disposed onthe short circuit board 253.

The discharge device 620 may include a capacitor, a discharge tube, or adiode. The discharge device 620 may have a voltage rating in the rangeof about 1.2 to 5 times that of the LED unit 632. And the voltage ratingof the capacitor may be between 200-600 V, for example. In addition, ifthe discharge device 620 includes a capacitor, the capacitor can achievea function of filtering when power is normally supplied. In thisfunction, the discharge device 620 may be a component of the filteringcircuit 520.

In various embodiments of the LED tube lamp according to thisdisclosure, each of the two end caps respectively coupled to twoopposite ends of the lamp tube may comprise at least one opening whichpenetrates through the end cap. In such case, (at least a component of)the protection circuit may preferably be positioned closer to the atleast one opening of the end cap than some other electronic componentsof the power supply (module) are, in order to facilitate heatdissipating or radiating by the protection circuit.

FIG. 22A is a block diagram of the driving circuit according to anembodiment of the present invention. Referring to FIG. 22A, the drivingcircuit includes a controller 1531, and a conversion circuit 1532 forpower conversion based on a current source, for driving the LED moduleto emit light. Conversion circuit 1532 includes a switching circuit 1535and an energy storage circuit 1538. And conversion circuit 1532 iscoupled to filtering output terminals 521 and 522 to receive and thenconvert a filtered signal, under the control by controller 1531, into adriving signal at driving output terminals 1521 and 1522 for driving theLED module. Under the control by controller 1531, the driving signaloutput by conversion circuit 1532 comprises a steady current, making theLED module emitting steady light.

FIG. 22B is a schematic diagram of the driving circuit according to anembodiment of the present invention. Referring to FIG. 22B, a drivingcircuit 1630 in this embodiment comprises a buck DC-to-DC convertercircuit having a controller 1631 and a converter circuit. The convertercircuit includes an inductor 1632, a diode 1633 for “freewheeling” ofcurrent, a capacitor 1634, and a switch 1635. Driving circuit 1630 iscoupled to filtering output terminals 521 and 522 to receive and thenconvert a filtered signal into a driving signal for driving an LEDmodule connected between driving output terminals 1521 and 1522.

In this embodiment, switch 1635 comprises a metal-oxide-semiconductorfield-effect transistor (MOSFET) and has a first terminal coupled to theanode of freewheeling diode 1633, a second terminal coupled to filteringoutput terminal 522, and a control terminal coupled to controller 1631used for controlling current conduction or cutoff between the first andsecond terminals of switch 1635. Driving output terminal 1521 isconnected to filtering output terminal 521, and driving output terminal1522 is connected to an end of inductor 1632, which has another endconnected to the first terminal of switch 1635. Capacitor 1634 iscoupled between driving output terminals 1521 and 1522, to stabilize thevoltage between driving output terminals 1521 and 1522. Freewheelingdiode 1633 has a cathode connected to driving output terminal 1521.

Next, a description follows as to an exemplary operation of drivingcircuit 1630.

Controller 1631 is configured for determining when to turn switch 1635on (in a conducting state) or off (in a cutoff state), according to acurrent detection signal S535 and/or a current detection signal S531.For example, in some embodiments, controller 1631 is configured tocontrol the duty cycle of switch 1635 being on and switch 1635 beingoff, in order to adjust the size or magnitude of the driving signal.Current detection signal S535 represents the magnitude of currentthrough switch 1635. Current detection signal S531 represents themagnitude of current through the LED module coupled between drivingoutput terminals 1521 and 1522. According to any of current detectionsignal S535 and current detection signal S531, controller 1631 canobtain information on the magnitude of power converted by the convertercircuit. When switch 1635 is switched on, a current of a filtered signalis input through filtering output terminal 521, and then flows throughcapacitor 1634, driving output terminal 1521, the LED module, inductor1632, and switch 1635, and then flows out from filtering output terminal522. During this flowing of current, capacitor 1634 and inductor 1632are performing storing of energy. On the other hand, when switch 1635 isswitched off, capacitor 1634 and inductor 1632 perform releasing ofstored energy by a current flowing from freewheeling capacitor 1633 todriving output terminal 1521 to make the LED module continuing to emitlight.

It's worth noting that capacitor 1634 is an optional element, so it canbe omitted and is thus depicted in a dotted line in FIG. 22B. In someapplication environments, the natural characteristic of an inductor tooppose instantaneous change in electric current passing through theinductor may be used to achieve the effect of stabilizing the currentthrough the LED module, thus omitting capacitor 1634.

FIG. 22C is a schematic diagram of the driving circuit according to anembodiment of the present invention. Referring to FIG. 22C, a drivingcircuit 1930 in this embodiment comprises a buck DC-to-DC convertercircuit having a controller 1931 and a converter circuit. The convertercircuit includes an inductor 1932, a diode 1933 for “freewheeling” ofcurrent, a capacitor 1934, and a switch 1935. Driving circuit 1930 iscoupled to filtering output terminals 521 and 522 to receive and thenconvert a filtered signal into a driving signal for driving an LEDmodule connected between driving output terminals 1521 and 1522.

Inductor 1932 has an end connected to filtering output terminal 521 anddriving output terminal 1522, and another end connected to a first endof switch 1935. Switch 1935 has a second end connected to filteringoutput terminal 522, and a control terminal connected to controller 1931to receive a control signal from controller 1931 for controlling currentconduction or cutoff of switch 1935. Freewheeling diode 1933 has ananode coupled to a node connecting inductor 1932 and switch 1935, and acathode coupled to driving output terminal 1521. Capacitor 1934 iscoupled to driving output terminals 1521 and 1522, to stabilize thedriving of the LED module coupled between driving output terminals 1521and 1522.

Controller 1931 is configured for controlling when to turn switch 1935on (in a conducting state) or off (in a cutoff state), according to acurrent detection signal S531 and/or a current detection signal S535.When switch 1935 is turned on, a current is input through filteringoutput terminal 521, and then flows through inductor 1932 and switch1935, and then flows out from filtering output terminal 522. During thisflowing of current, the current through inductor 1932 increases withtime, so inductor 1932 is in a state of storing energy; but the voltageof capacitor 1934 decreases with time, so capacitor 1934 is in a stateof releasing energy to keep the LED module continuing to emit light. Onthe other hand, when switch 1935 is turned off, inductor 1932 is in astate of releasing energy and its current decreases with time. In thiscase, the current through inductor 1932 circulates through freewheelingdiode 1933, driving output terminals 1521 and 1522, and back to inductor1932. During this circulation, capacitor 1934 is in a state of storingenergy and its voltage increases with time.

It's worth noting that capacitor 1934 is an optional element, so it canbe omitted and is thus depicted in a dotted line in FIG. 22C. Whencapacitor 1934 is omitted and switch 1935 is turned on, the currentthrough inductor 1932 doesn't flow through driving output terminals 1521and 1522, thereby making the LED module not emit light. On the otherhand, when switch 1935 is turned off, the current through inductor 1932flows through freewheeling diode 1933 and then the LED module to makethe LED module emit light. Therefore, by controlling the time that theLED module emits light, and the magnitude of current through the LEDmodule, the average luminance of the LED module can be stabilized to beabove a defined value, thus also achieving the effect of emitting asteady light.

FIG. 23A is a schematic diagram of the mode switching circuit in an LEDlamp according to an embodiment of the present invention. Referring toFIG. 23A, a mode switching circuit 680 includes a mode switch 681suitable for use with the driving circuit 1630 in FIG. 22B. Referring toFIGS. 23A and 22B, mode switch 681 has three terminals 683, 684, and685, wherein terminal 683 is coupled to driving output terminal 1522,terminal 684 is coupled to filtering output terminal 522, and terminal685 is coupled to the inductor 1632 in driving circuit 1630.

When mode switching circuit 680 determines to perform a first drivingmode, mode switch 681 conducts current in a first conductive paththrough terminals 683 and 685 and a second conductive path throughterminals 683 and 684 is in a cutoff state. In this case, driving outputterminal 1522 is coupled to inductor 1632, and therefore driving circuit1630 is working normally, which working includes receiving a filteredsignal from filtering output terminals 521 and 522 and then transformingthe filtered signal into a driving signal, output at driving outputterminals 1521 and 1522 for driving the LED module.

When mode switching circuit 680 determines to perform a second drivingmode, mode switch 681 conducts current in the second conductive paththrough terminals 683 and 684 and the first conductive path throughterminals 683 and 685 is in a cutoff state. In this case, driving outputterminal 1522 is coupled to filtering output terminal 522, and thereforedriving circuit 1630 stops working, and a filtered signal is inputthrough filtering output terminals 521 and 522 to driving outputterminals 1521 and 1522 for driving the LED module, while bypassinginductor 1632 and switch 1635 in driving circuit 1630.

FIG. 23B is a schematic diagram of the mode switching circuit in an LEDlamp according to an embodiment of the present invention. Referring toFIG. 23B, a mode switching circuit 780 includes a mode switch 781suitable for use with the driving circuit 1630 in FIG. 22B. Referring toFIGS. 23B and 22B, mode switch 781 has three terminals 783, 784, and785, wherein terminal 783 is coupled to filtering output terminal 522,terminal 784 is coupled to driving output terminal 1522, and terminal785 is coupled to switch 1635 in driving circuit 1630.

When mode switching circuit 780 determines to perform a first drivingmode, mode switch 781 conducts current in a first conductive paththrough terminals 783 and 785 and a second conductive path throughterminals 783 and 784 is in a cutoff state. In this case, filteringoutput terminal 522 is coupled to switch 1635, and therefore drivingcircuit 1630 is working normally, which working includes receiving afiltered signal from filtering output terminals 521 and 522 and thentransforming the filtered signal into a driving signal, output atdriving output terminals 1521 and 1522 for driving the LED module.

When mode switching circuit 780 determines to perform a second drivingmode, mode switch 781 conducts current in the second conductive paththrough terminals 783 and 784 and the first conductive path throughterminals 783 and 785 is in a cutoff state. In this case, driving outputterminal 1522 is coupled to filtering output terminal 522, and thereforedriving circuit 1630 stops working, and a filtered signal is inputthrough filtering output terminals 521 and 522 to driving outputterminals 1521 and 1522 for driving the LED module, while bypassinginductor 1632 and switch 1635 in driving circuit 1630.

FIG. 23C is a schematic diagram of the mode switching circuit in an LEDlamp according to an embodiment of the present invention. Referring toFIG. 23C, a mode switching circuit 1880 includes mode switches 1881 and1882 suitable for use with the driving circuit 1930 in FIG. 22C.Referring to FIGS. 23C and 22C, mode switch 1881 has three terminals1883, 1884, and 1885, wherein terminal 1883 is coupled to driving outputterminal 1521, terminal 1884 is coupled to filtering output terminal521, and terminal 1885 is coupled to freewheeling diode 1933 in drivingcircuit 1930. And mode switch 1882 has three terminals 1886, 1887, and1888, wherein terminal 1886 is coupled to driving output terminal 1522,terminal 1887 is coupled to filtering output terminal 522, and terminal1888 is coupled to filtering output terminal 521.

When mode switching circuit 1880 determines to perform a first drivingmode, mode switch 1881 conducts current in a first conductive paththrough terminals 1883 and 1885 and a second conductive path throughterminals 1883 and 1884 is in a cutoff state, and mode switch 1882conducts current in a third conductive path through terminals 1886 and1888 and a fourth conductive path through terminals 1886 and 1887 is ina cutoff state. In this case, driving output terminal 1521 is coupled tofreewheeling diode 1933, and filtering output terminal 521 is coupled todriving output terminal 1522. Therefore, driving circuit 1930 is workingnormally, which working includes receiving a filtered signal fromfiltering output terminals 521 and 522 and then transforming thefiltered signal into a driving signal, output at driving outputterminals 1521 and 1522 for driving the LED module.

When mode switching circuit 1880 determines to perform a second drivingmode, mode switch 1881 conducts current in the second conductive paththrough terminals 1883 and 1884 and the first conductive path throughterminals 1883 and 1885 is in a cutoff state, and mode switch 1882conducts current in the fourth conductive path through terminals 1886and 1887 and the third conductive path through terminals 1886 and 1888is in a cutoff state. In this case, driving output terminal 1521 iscoupled to filtering output terminal 521, and filtering output terminal522 is coupled to driving output terminal 1522. Therefore, drivingcircuit 1930 stops working, and a filtered signal is input throughfiltering output terminals 521 and 522 to driving output terminals 1521and 1522 for driving the LED module, while bypassing freewheeling diode1933 and switch 1935 in driving circuit 1930.

FIG. 23D is a schematic diagram of the mode switching circuit in an LEDlamp according to an embodiment of the present invention. Referring toFIG. 23D, a mode switching circuit 1980 includes mode switches 1981 and1982 suitable for use with the driving circuit 1930 in FIG. 22C.Referring to FIGS. 23D and 22C, mode switch 1981 has three terminals1983, 1984, and 1985, wherein terminal 1983 is coupled to filteringoutput terminal 522, terminal 1984 is coupled to driving output terminal1522, and terminal 1985 is coupled to switch 1935 in driving circuit1930. And mode switch 1982 has three terminals 1986, 1987, and 1988,wherein terminal 1986 is coupled to filtering output terminal 521,terminal 1987 is coupled to driving output terminal 1521, and terminal1988 is coupled to driving output terminal 1522.

When mode switching circuit 1980 determines to perform a first drivingmode, mode switch 1981 conducts current in a first conductive paththrough terminals 1983 and 1985 and a second conductive path throughterminals 1983 and 1984 is in a cutoff state, and mode switch 1982conducts current in a third conductive path through terminals 1986 and1988 and a fourth conductive path through terminals 1986 and 1987 is ina cutoff state. In this case, driving output terminal 1522 is coupled tofiltering output terminal 521, and filtering output terminal 522 iscoupled to switch 1935. Therefore, driving circuit 1930 is workingnormally, which working includes receiving a filtered signal fromfiltering output terminals 521 and 522 and then transforming thefiltered signal into a driving signal, output at driving outputterminals 1521 and 1522 for driving the LED module.

When mode switching circuit 1980 determines to perform a second drivingmode, mode switch 1981 conducts current in the second conductive paththrough terminals 1983 and 1984 and the first conductive path throughterminals 1983 and 1985 is in a cutoff state, and mode switch 1982conducts current in the fourth conductive path through terminals 1986and 1987 and the third conductive path through terminals 1986 and 1988is in a cutoff state. In this case, driving output terminal 1521 iscoupled to filtering output terminal 521, and filtering output terminal522 is coupled to driving output terminal 1522. Therefore, drivingcircuit 1930 stops working, and a filtered signal is input throughfiltering output terminals 521 and 522 to driving output terminals 1521and 1522 for driving the LED module, while bypassing freewheeling diode1933 and switch 1935 in driving circuit 1930.

It's worth noting that the mode switches in the above embodiments mayeach comprise, for example, a single-pole double-throw switch, orcomprise two semiconductor switches (such as metal oxide semiconductortransistors), for switching a conductive path on to conduct currentwhile leaving the other conductive path cutoff. Each of the twoconductive paths provides a path for conducting the filtered signal,allowing the current of the filtered signal to flow through one of thetwo paths, thereby achieving the function of mode switching orselection. For example, with reference to FIGS. 14A, 14B, and 14D inaddition, when the lamp driving circuit 505 is not present and the LEDtube lamp 500 is directly supplied by the AC power supply 508, the modeswitching circuit may determine on performing a first driving mode inwhich the driving circuit (such as driving circuit 1530, 1630, 1730,1830, or 1930) transforms the filtered signal into a driving signal of alevel meeting a required level to properly drive the LED module to emitlight. On the other hand, when the lamp driving circuit 505 is present,the mode switching circuit may determine on performing a second drivingmode in which the filtered signal is (almost) directly used to drive theLED module to emit light; or alternatively the mode switching circuitmay determine on performing the first driving mode to drive the LEDmodule to emit light.

FIG. 24A is a block diagram of a power supply module in an LED tube lampaccording to an embodiment of the present invention. Compared to thatshown in FIG. 60A, the present embodiment comprises the rectifyingcircuits 510 and 540, the filtering circuit 520, the LED driving module530, the two filament-simulating circuits 1560, and further comprises anauxiliary power module 2510. The auxiliary power module 2510 is coupledbetween the filtering output terminal 521 and 522. The auxiliary powermodule 2510 detects the filtered signal in the filtering outputterminals 521 and 522, and determines whether providing an auxiliarypower to the filtering output terminals 521 and 522 based on thedetected result. When the supply of the filtered signal is stopped or alevel thereof is insufficient, i.e., when a drive voltage for the LEDmodule is below a defined voltage, the auxiliary power module providesauxiliary power to keep the LED driving module 530 continuing to emitlight. The defined voltage is determined according to an auxiliary powervoltage of the auxiliary power module 2510. The rectifying circuit 540and the filament-simulating circuit 1560 may be omitted and aretherefore depicted by dotted lines.

FIG. 24B is a block diagram of a power supply module in an LED tube lampaccording to an embodiment of the present invention. Compared to thatshown in FIG. 24A, the present embodiment comprises the rectifyingcircuits 510 and 540, the filtering circuit 520, the LED driving module530, the two filament-simulating circuits 1560, and the LED drivingmodule 530 further comprises the driving circuit 1530 and the LED module630. The auxiliary power module 2510 is coupled between the drivingoutput terminals 1521 and 1522.

The auxiliary power module 2510 detects the driving signal in thedriving output terminals 1521 and 1522, and determines whether toprovide an auxiliary power to the driving output terminals 1521 and 1522based on the detected result. When the driving signal is no longer beingsupplied or a level thereof is insufficient, the auxiliary power moduleprovides the auxiliary power to keep the LED module 630 continuouslylight. The rectifying circuit 540 and the filament-simulating circuit1560 may be omitted and are therefore depicted by dotted lines.

FIG. 24C is a schematic diagram of an auxiliary power module accordingto an embodiment of the present invention. The auxiliary power module2610 comprises an energy storage unit 2613 and a voltage detectioncircuit 2614. The auxiliary power module further comprises an auxiliarypower positive terminal 2611 and an auxiliary power negative terminal2612 for being respectively coupled to the filtering output terminals521 and 522 or the driving output terminals 1521 and 1522. The voltagedetection circuit 2614 detects a level of a signal at the auxiliarypower positive terminal 2611 and the auxiliary power negative terminal2612 to determine whether releasing outward the power of the energystorage unit 2613 through the auxiliary power positive terminal 2611 andthe auxiliary power negative terminal 2612.

In the present embodiment, the energy storage unit 2613 is a battery ora supercapacitor. When a voltage difference of the auxiliary powerpositive terminal 2611 and the auxiliary power negative terminal 2612(the drive voltage for the LED module) is higher than the auxiliarypower voltage of the energy storage unit 2613, the voltage detectioncircuit 2614 charges the energy storage unit 2613 by the signal in theauxiliary power positive terminal 2611 and the auxiliary power negativeterminal 2612. When the drive voltage is lower than the auxiliary powervoltage, the energy storage unit 2613 releases the stored energy outwardthrough the auxiliary power positive terminal 2611 and the auxiliarypower negative terminal 2612.

The voltage detection circuit 2614 comprises a diode 2615, a bipolarjunction transistor (BJT) 2616 and a resistor 2617. A positive end ofthe diode 2615 is coupled to a positive end of the energy storage unit2613 and a negative end of the diode 2615 is coupled to the auxiliarypower positive terminal 2611. The negative end of the energy storageunit 2613 is coupled to the auxiliary power negative terminal 2612. Acollector of the BJT 2616 is coupled to the auxiliary power positiveterminal 2611, and the emitter thereof is coupled to the positive end ofthe energy storage unit 2613. One end of the resistor 2617 is coupled tothe auxiliary power positive terminal 2611 and the other end is coupledto a base of the BJT 2616. When the collector of the BJT 2616 is acut-in voltage higher than the emitter thereof, the resistor 2617conducts the BJT 2616. When the power source provides power to the LEDtube lamp normally, the energy storage unit 2613 is charged by thefiltered signal through the filtering output terminals 521 and 522 andthe conducted BJT 2616 or by the driving signal through the drivingoutput terminals 1521 and 1522 and the conducted BJT 2616 unit that thecollector-emitter voltage of the BJT 2616 is lower than or equal to thecut-in voltage. When the filtered signal or the driving signal is nolonger being supplied or the level thereof is insufficient, the energystorage unit 2613 provides power through the diode 2615 to keep the LEDdriving module 530 or the LED module 630 continuously light.

It is worth noting that in some embodiments, the maximum voltage of thecharged energy storage unit 2613 is the cut-in voltage of the BJT 2616lower than a voltage difference applied between the auxiliary powerpositive terminal 2611 and the auxiliary power negative terminal 2612.The voltage difference provided between the auxiliary power positiveterminal 2611 and the auxiliary power negative terminal 2612 is aturn-on voltage of the diode 2615 lower than the voltage of the energystorage unit 2613. Hence, when the auxiliary power module 2610 providespower, the voltage applied at the LED module 630 is lower (about the sumof the cut-in voltage of the BJT 2616 and the turn-on voltage of thediode 2615). In the embodiment shown in the FIG. 24B, the brightness ofthe LED module 630 is reduced when the auxiliary power module suppliespower thereto. Thereby, when the auxiliary power module is applied to anemergency lighting system or a constant lighting system, the userrealizes the main power supply, such as commercial power, is abnormaland then performs necessary precautions therefor.

The LED tube lamps according to various different embodiments of thepresent invention are described as above.

According to examples of the power supply module, the external drivingsignal may be low frequency AC signal (e.g., commercial power), highfrequency AC signal (e.g., that provided by a ballast), or a DC signal(e.g., that provided by a battery), input into the LED tube lamp througha drive architecture of single-end power supply or dual-end powersupply. For the drive architecture of dual-end power supply, theexternal driving signal may be input by using only one end thereof assingle-end power supply.

The LED tube lamp may omit the rectifying circuit when the externaldriving signal is a DC signal.

According to the design of the LED lighting module according to someembodiments, the LED lighting module may comprise the LED module and adriving circuit or only the LED module.

According to the design of the mode determination circuit in someembodiments, the mode determination circuit may be connected to therectifying circuit for detecting the state of the property of therectified signal to selectively determine whether to perform a firstmode or a second mode of lighting according to the state of the propertyof the rectified signal. Accordingly, the LED tube lamp is compatiblewith different types of the electrical ballasts, e.g. electronicballasts and inductive (or magnetic) ballasts.

According to the design of the mode determination circuit in someembodiments, the mode determination circuit may be connected to theelectrical ballast for detecting the state of the property of theexternal driving signal to selectively determine whether to perform afirst mode or a second mode of lighting according to the state of theproperty of the external driving signal. Accordingly, the LED tube lampis compatible with different types of the electrical ballasts, e.g.electronic ballasts and inductive ballasts.

According to the design of the mode determination circuit in someembodiments, the mode determination circuit includes a ballast interfacecircuit as an interface between the LED tube lamp and electrical ballastused to supply the LED tube lamp. Accordingly, the LED tube lamp iscompatible with different types of the electrical ballasts, e.g.electronic ballasts and inductive ballasts.

According to the design of the mode determination circuit in someembodiments, the mode determination circuit includes a discharge deviceto be conducted when welding defects existed between the positiveelectrodes of the LED unit and the negative electrodes of the LED unitfor preventing the LED unit from arcing.

The above-mentioned features can be accomplished in any combination toimprove the LED tube lamp, and the above embodiments are described byway of example only. The present invention is not herein limited, andmany variations are possible without departing from the spirit of thepresent invention and the scope as defined in the appended claims.

What is claimed is:
 1. A mode switching circuit configured to change asignal path in a light-emitting diode (LED) tube lamp, the modeswitching circuit comprising: at least one switch, configured to receivea filtered signal as a driving signal to drive an LED module in the LEDtube lamp to emit light, and when a frequency of an external drivingsignal received by the LED tube lamp is higher than a predefined modeswitching frequency, output the driving signal to the LED module,wherein the LED tube lamp comprises an auxiliary power module coupled tothe mode switching circuit and the LED module, and the auxiliary powermodule is configured such that when the driving signal is unable todrive the LED module to emit light, the auxiliary power module providesauxiliary power for the LED module to emit light, and wherein the modeswitching circuit is on a printed circuit board and is electricallyconnected to the LED module on a bendable circuit sheet in the LED tubelamp, wherein the bendable circuit sheet is disposed below the printedcircuit board to be electrically connected to the printed circuit boardby soldering.
 2. The mode switching circuit according to claim 1,wherein: the bendable circuit sheet includes a first surface and asecond surface; a plurality of first soldering pads are formed on thefirst surface of the bendable circuit sheet; the printed circuit boardincludes a top surface and a bottom surface; a plurality of secondsoldering pads are formed on the top surface of the printed circuitboard; a plurality of third soldering pads respectively corresponding tothe plurality of second soldering pads are formed on the bottom surfaceof the printed circuit board; and the plurality of first soldering padson the first surface of the bendable circuit sheet are electricallyconnected to the plurality of third soldering pads on the bottom surfaceof the printed circuit board by soldering.
 3. The mode switching circuitaccording to claim 2, wherein the printed circuit board further includesa plurality of through holes correspondingly passing through theplurality of second and third soldering pads on the top surface and thebottom surface of the printed circuit board, wherein at least one of theplurality of through holes is filled with a soldering material toelectrically connect to the bendable circuit sheet during a solderingprocess.
 4. The mode switching circuit according to claim 3, wherein thebendable circuit sheet further includes at least one notch disposed onan edge of an end of the bendable circuit sheet, the at least one notchaligned with the at least one of the plurality of through holes andsoldered to the printed circuit board.
 5. The LED tube lamp according toclaim 1, wherein the auxiliary power module includes an auxiliary powerpositive terminal, an auxiliary power negative terminal, an energystorage unit, and a voltage detection circuit; the auxiliary powerpositive and negative terminals are coupled to the LED module; and thevoltage detection circuit is configured to detect a level of signal atthe auxiliary power positive and negative terminals in order todetermine whether to release energy or power of the energy storage unitto the LED module through the auxiliary power positive and negativeterminals.
 6. The mode switching circuit according to claim 1, whereinthe at least one switch is further configured to cause a driving circuitin the LED tube lamp to receive the filtered signal and produce anotherdriving signal to drive the LED module to emit light when the frequencyof the external driving signal received by the LED tube lamp is lowerthan the predefined mode switching frequency.
 7. The mode switchingcircuit according to claim 1, wherein the signal path includes a firstpath extending from the external driving signal received by the LED tubelamp and including a rectifying circuit, a filtering circuit, the modeswitching circuit, and the LED module.
 8. The mode switching circuitaccording to claim 7, wherein the signal path includes a second pathextending from the external driving signal received by the LED tube lampand including the rectifying circuit, the filtering circuit, the LEDmodule, and a driving circuit configured to drive the LED module.
 9. Themode switching circuit according to claim 1, wherein the at least oneswitch includes a mode switch including a single pole double throwswitch and/or an electronic switch.
 10. The mode switching circuitaccording to claim 1, wherein the at least one switch includes two modeswitches, each of which includes a single pole double throw switchand/or an electronic switch.